My intention:
To establish infirmity, dependency, and the inadequacy of moral determination; ruled by conscience. To further establish; that "The love of Christ", in v.35, Paul intends to be the same as, the "the love of God, which is in Christ Jesus our Lord", in v. 39; and that this love must be greater, than everything, that Paul sets against it; from v.35-39.
Infirmity and dependency, demonstrated in deliverance
(Rom 7:1) Know ye not, brethren, (for I speak to them that know the law,) how that the law hath dominion over a man as long as he liveth?
Expressed in terms of the law, to hearers who knew the law, Paul expounds, in the form of similitude, on marriage under the law.
(Rom 7:2) For the woman which hath an husband is bound by the law to her husband so long as he liveth; but if the husband be dead, she is loosed from the law of her husband.
(Rom 7:3) So then if, while her husband liveth, she be married to another man, she shall be called an adulteress: but if her husband be dead, she is free from that law; so that she is no adulteress, though she be married to another man.
By comprehension, of the "...great mystery", which he alludes to later in (Eph 5:30-32), he interprets marriage as the covenant shadow; fulfilled by the spiritual union, of Christ, and the Church.
The connection to Ephesians is justification, for metaphorical interpretation
Eph 5:30 For we are members of his body, of his flesh, and of his bones.
31 For this cause shall a man leave his father and mother, and shall be joined unto his wife, and they two shall be one flesh.
32 This is a great mystery: but I speak concerning Christ and the church.
33 Nevertheless let every one of you in particular so love his wife even as himself; and the wife see that she reverence her husband.
I also include v. 33, to serve as contrast. Paul intends this distinction, between the preceding two verses, and immediate context; authors original intent, with his audience. This is clear by his usage of "Nevertheless
Not to dwell longer on the mystical aspect of the subject (M. R. Vincent)."
(M. R. Vincent, The writings of John. The Gospel. The Epistles. The Apocalypse.* Word Studies in the New Testament (Vol 2), New York, Scribner (1887).
(Provision of Ethics) Marvin R. Vincent, D.D.
Baldwin Professor of Sacred Literature in Union Theological Seminary New York.
This entire chapter of Eph. 5 is instructive rhetoric. v. 29 is a transition to this segue (Allusion of Metonymy), which alludes to a mystical interpretation ending in v.32. So it is. v.29 "For no man ever yet hated his own flesh; but nourisheth and cherisheth it, even as the Lord the church:" This last segment is metonymic; broader than synecdoche, because its application is not apparent in the immediate context.
Notice, (Rom 7:4) being antecedent, has the interpretation of (Eph 5:30-32) "Wherefore, my brethren, ye also are become dead to the law by the body of Christ; that ye should be married to another, even to him who is raised from the dead, that we should bring forth fruit unto God." Later in Ephesians it appears to be a secondary thought, that he cut's short with "Nevertheless...".
The interpretation
In the process of interpreting the implications of a spouses liberty, from the law of her husband, upon the event of his death, and her freedom to marry another; he reveals this mystery of impunity, from condemnation under the law. The law is personified.
"As long - So long, and no longer. As it liveth - The law is here spoken of, by a common figure, as a person, to which, as to an husband, life and death are ascribed. But he speaks indifferently of the law being dead to us, or we to it, the sense being the same (John Wesley's Notes on the Bible
Pub. (1755-1766); public domain)." See Rom. 7:1 of this commentary.
Summary of interpretation
So, by the death of one who fulfilled the law, all are free to be espoused to another, whose law is the Spirit of Life (Rom 7:6 following); predicated on his fulfillment of that law that condemned; his death which made it possible to be espoused to himself; the risen Christ, and that, by faith alone in His death as the complete satisfaction of Divine Justice (Rom 4:4-8 following).
Justification
(Rom 7:6) But now we are delivered from the law, that being dead wherein we were held; that we should serve in newness of spirit, and not in the oldness of the letter.
Compare the parallel structures of (Rom 7:4) with that of (Rom 7:6) above; where "raised from the dead" there, corresponds to "newness of spirit." here, just as "dead to the law" there corresponds to "...delivered from the law...being dead" here. They are in harmony. It is the basis for this assertion (mine) "...espoused to another, whose law is the Spirit of Life;", which also agrees with
(Rom 8:2) "For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death."
Faith satisfies Divine justice; and reckoning of debt, absolved by beneficence
(Rom 4:4-8) Now to him that worketh is the reward not reckoned of grace, but of debt. 5 But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness.
6 Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works,
7 Saying, Blessed are they whose iniquities are forgiven, and whose sins are covered.
8 Blessed is the man to whom the Lord will not impute sin.
Conscience Vs. Law
Moral determination proven inadequate, men ruled by conscience fall under the same
Paul establishes a relationship of equality with regard to law and conscience; both Jew, and Greek, in terms of an identical end result; the only possible exception; sinlesness, in either case. In v.13 with respect to the law, it is "...doers of the law shall be justified.", and in v.12 it is implied in this "For as many as have sinned."
Rom 2:12 "For as many as have sinned without law shall also perish without law: and as many as have sinned in the law shall be judged by the law;
13 For not the hearers of the law are just before God, but the doers of the law shall be justified.
14 For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves:
15 Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another;)
Rom 2:16 In the day when God shall judge the secrets of men by Jesus Christ according to my gospel."
Before this edit, I had initially made reference to the following verse in 1 Peter, in this fashion "...the law of conscience, which ruled men in the days of Noah, proving it to be a betrayer." This is one of the mystical references to baptism. Another one being related to The Exodus, The cloud that follows, and Israel passing through the Red Sea, along with the fountain Rock, which Paul identifies as Christ. I didn't feel that I need that support any longer. However, holding to the context of baptism; the ark is an obvious type of Christ, as conductor, from one world to the next, as eight souls passed through the flood, from the antediluvian world, to the new. Let this remain an unsupported assertion. it's just ...interesting.
(1 Peter 3:20) "...once the long-suffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water."
(Pr. 14:12)"There is a way that seems right unto a man, but the end thereof are the ways of death."
Concerning "Right - There are some evil courses which men may think to be lawful and good. The end - The event shews that they were sinful and destructive.(John Wesley's Notes)."
All of Paul's reasoning above, argues against notions, of self reliance.
The greatness of this love
The love of Christ" v.35, and "The love of God in Christ" v.39 are the same
The relationship between both instances of love, is constructed in a bookend fashion; encapsulating everything that Paul mentions between them. Paul does not refer to either one in between: ex.
(see Addendum: Also: Simply a Christian), and the body of opposition stands in equal relation to both instances. Unchecked, the opposition would separate; the object of separation, is immovable; and separation is impossible.
Conclusion:
A comparison, and contrast; of infirmity, dependency, and the impotency of moral determination; with that love, which proves unshakable; by anything Paul names here; cannot result, in a logical determination, of equality.
However, the OP makes reference, to these two verses.
(Rom 5:5) "And hope maketh not ashamed; because the love of God is shed abroad in our hearts by the Holy Ghost which is given unto us."
(1Jn 4:19) We love him, because he first loved us.
Now, all of a sudden, I can also see it, both ways; in terms of a reciprocating union. Where I see two equally immovable objects. God, as the original source of love, who gives the Holy Spirit; the agent of God's love, both to, and through; and all by means of a mediary; Jesus Christ. Again, that will have to remain an unsupported assertion. Still, Interesting.
Being that God is the original fount of love, I still maintain that it should be understood as, the love of God.
Addendum:
In further review; pre-edit, I also recognize the following language to be too strong; being pregnant with implication, and reeking of hubris. For this I apologize.
"It is absurd to think that Paul would labor so meticulously, and so ardently, to disparage any grounds for hope; predicated on the will, determination, or the passion of man; only to later imply, by omission, that there exists such a love; equal to Christ's own; that he does not impart."
Aslo:
As Simply a Christian points out here; (Rom 8:37), provides unifying support, as it is placed concentrically, to the opposition; "...more than conquerors through him that loved us." It also proves more efficient, by taking a shorter path, to a definitive observation; one, that I wish I had seen first.
As for this.
"(-1) for identifying "him who loved us" as Christ without any supporting evidence and then building a case on that sand foundation."
(Gal 2:20) I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.
We should not quibble over miles or millimeters. While some things must be viewed under a microscope, others can only be seen, from a mile high view.