Marriage is a very different institution now from first century Roman times. In Roman times, there was a significant power imbalance because of its highly patriarchal society and law. Paul goes to some lengths to redress this power imbalance in a number of contexts without completely rewriting Roman law. Here is a sample.
All relationships, regardless of their origin, are predicated on some level of trust. It is when this trust breaks down that abuse is created. The genesis of all abuse in any
relationship is abuse of that relationship by the stronger side and the responsibilities it entails. This can be seen in numerous cases.
Wives should be subject to their husbands as in the Lord (Eph 5:22) but this
must be balanced by the instruction that all Christians should be subject to one another
(Eph 5:21), AND, that husbands should love their wives as Christ loved the Church and
gave Himself for her (Eph 5:25)! Therefore, this does not give licence to men to abuse
their wives, quite the contrary; it increases men's responsibility to be kind and supportive.
Masters & Slaves
“Slaves, be obedient to your masters” (Eph 6:5), but this must be balanced by Paul's instruction to masters to stop threatening (read abusing) slaves because in heaven we will all be equal and there is no partiality (Eph 6:9). Therefore, this does not give licence to masters or work bosses to abuse employees but increases their responsibility to be kind and supportive.
Governors and Citizens
Christians are instructed to be subject to every governing authority (Rom 13:1-7), but this must be balanced by God's instructions to rulers and judges (eg, 2 Chron 19:5-11) to exercise their authority on God's behalf without partiality or bribes. Therefore, this does not give licence to rulers to abuse their subjects but increases their responsibility to be kind, just and fair.
Parents and Children
Children are instructed to obey and honor parents (Ex 20:12, Deut 5:16, 27:16, Eph 6:1-3, Col 3:20, Prov 6:20, 23:22, etc) but this must be balanced by the instruction that fathers should not exasperate (read abuse) children (Eph 6:4, Col 3:21) but must take their parental responsibility very seriously (Ps 127:3-5, Deut 6:6, 7, Titus 2:7, See also 1 Peter 5:2, 3). Therefore, this does not give licence to parents (most often fathers) to abuse their children but increases their responsibility to be examples of the good, kind and just.
God and Us
The most extreme example of this is our relationship with God. God is in a much more powerful situation by being omnipotent (Dan 4:17, 25, 35, Matt 19:26, Rev 19:6) and so takes correspondingly greater responsibility in our relationships. In fact, God
Biblical even takes responsibility for our sin and has implemented a plan to solve our sin problem (Rom 5:8, Gal 3:13, 2 Cor 5:21). In imitating God (John 13:34, 35, 15:12, 1 John 4:8, 11, 19, Eph 5:1, 2, Phil 2:5, 1 Cor 2:16, Luke 6:34, 35) we must do the same.
All these are examples of the principle that Jesus offered in Luke 12:48 – “to whom much
is given, much is required” – a sobering idea for those in responsibility in any relationship.
This pattern can and should be extrapolated to all relationships, because, even in largely equal relationships, there will be times when one side of the relationship has an advantage over the other. For example, when parents become aged and dependent on their children, children should not exploit their parents with financial, verbal or physical abuse.