We interpret the Samaritan woman's culture too much in the light of Western Christian culture. Monogamy wasn't the standard. Only men could divorce. Women weren't allowed. The word husband also meant man. If the culture then was like modern Middle Eastern culture, women weren't allowed to be alone, but would have a close relative as a guardian. The five men may not have been all husbands. The man not her own may have been a close relative as a guardian. The first man may have been her father's family, and she may have seen the death of four men; some being husbands. However, her going to the well alone seems strange for that culture. Bringing her husband or guardian into the conversation was the proper thing to do.
John 4:29 is the verse that explains why Jesus asked, "Go, call your husband, and come here.” (in John 4:16, ESV) Of course it is literally, "Go, call your man..." ὕπαγε φώνησον ⸉τὸν ἄνδρα σου (NA28).
Come, see a man who told me all that I ever did. Can this be the Christ?” 30 They went out of the town and were coming to him.
(John 4:29–30, ESV)
What the following question, previous asked, tells us is we don't really know the details of what five men meant, but she did and was preoccupied enough with it to describe it as telling all she ever did. The town was also convinced.
See John 4:18 What is the woman's reputation in town?
Many see the woman's questions as trying to sidetrack Jesus, but she was not. Those questions were central in Jesus reaching the Samaritans. The Samaritans expected the prophet Moses foretold to break down the barriers between the Jews and Samaritans, and what a barrier between a Jewish rabbi and Samaritan woman.
Here is a wide variety of interpretations.
The woman is issued three commands. She is to go, call and bring. These commands require that she, a woman, become a witness to a man. In her world, is that possible?
Jesus assumes it is and challenges her to believe that with him a woman’s witness can be judged reliable. In John’s Gospel the next time Jesus makes this type of request is in a garden outside a tomb where he says to Mary Magdalene, “Go to my brethren and say to them …” (Jn 20:17). You, a woman, go and tell the men.
If she is to become a spring for others, her family should be the first to benefit from the water of life that he offers her. As he creates a spring in her, Jesus challenges her to allow its waters to flow to those around her.
Bailey, K. E. (2008). Jesus through Middle Eastern Eyes: Cultural Studies in the Gospels (p. 208). Downers Grove, IL: IVP Academic.
Jesus stated that she lived with a man who was not her husband. Many assume this meant the woman lived with her boyfriend, but that is not stated. Perhaps she needed help and lived with a distant relative, or in some other undesirable arrangement, in order to survive. Jesus was not nailing her to the cross of justice, but instead was letting her know that he knew everything about the pain she endured. This is certainly more in keeping with the Jesus we know from other instances in his life.
Lizorkin-Eyzenberg, Eli. The Jewish Gospel of John: Discovering Jesus, King of All Israel (p. 49). Jewish Studies for Christians. Kindle Edition.
Go, call thy husband (ὑπαγε φωνησον σου τον ἀνδρα [Hupage phōnēson sou ton andra]). Two imperatives (present active, first aorist active). Had she started to leave after her perplexed reply? Her frequent trips to the well were partly for her husband. We may not have all the conversation preserved, but clearly Jesus by this sudden sharp turn gives the woman a conviction of sin and guilt without which she cannot understand his use of water as a metaphor for eternal life.
Robertson, A. T. (1933). Word Pictures in the New Testament (John 4:16). Nashville, TN: Broadman Press.
4:16–17. In view of the ambiguity of the situation (see comment on 4:7), her statement, “I have no husband,” could mean “I am available.” Jesus removes the ambiguity, which stems from his refusal to observe customs that reflected ethnic and gender prejudice, not from any actual flirtation on his part.
Keener, C. S. (1993). The IVP Bible background commentary: New Testament (Jn 4:16–17). Downers Grove, IL: InterVarsity Press.
Ver. 16. Call thy husband.—(1) The husband was to have part in the saving gift, and so she was to be brought indirectly to confession of sin (Chrysostom, etc.; Lücke). (2) Christ would in this way lead her indirectly to a consciousness of her guilt (Calov., Neander, Tholuck, Stier, Luthardt). (3) He intended to give her a sign of His prophetic knowledge in the lower sphere of life, to gain her confidence for disclosures from the higher (Cyril, Schweizer; similarly Meyer). (4) Conformity to custom and to the idea of the law. Hitherto Jesus had influenced her after the manner of a missionary, as man with man. In her last request, expressing spiritual susceptibility, the woman came to the position of a catechumen. But, as a proselyte, she must not act without the knowledge of her husband. Meyer objects: The husband was in truth a paramour. True, they were not legally united. But the highest, most delicate social law lies somewhat deeper; she had given that man the rights of husband. If there was still a moral spark in the immoral connection, Christ had an eye to detect it. Even Stier and Tholuck have not been able to appropriate this interpretation. But it is connected on the one hand with the moral principle, Matth. 3:15; on the other with the principles in Matth. 10:12; 1 Cor. 7:15; 11:10, and with all those principles which distinguish the Evangelical church from the Roman Catholic in the manner of making proselytes.
[I must dissent from this interpretation as assuming a relation and a duty which did not exist. The words of Christ: Call thy husband, opened the wound at the tender spot where the cure was to begin, and were the first step in granting the woman’s request: Give me to drink. By a prophetic glance into her private life of shame, which, after five successive marriages, culminated in her present illegitimate relation, He at once effectually touched her conscience and challenged her faith in Him. Conviction of sin is the first indispensable condition of forgiveness, and is the beginning of conversion. She at once understood the intention, and her next word is a half confession of guilt, quickly followed by faith in the prophetic character of Christ.—P. S.]
Lange, J. P., & Schaff, P. (2008). A commentary on the Holy Scriptures: John (p. 158). Bellingham, WA: Logos Bible Software.