Some verses to consider regarding the Matt 5:39 discussion.
Matt 18:15-18
15 Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother.
16 But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established.
17 And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as an heathen man and a publican.
18 Verily I say unto you, Whatsoever ye shall bind on earth shall be bound in heaven: and whatsoever ye shall loose on earth shall be loosed in heaven.
KJV
2 John 9-11
9 Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son.
10 If there come any unto you, and bring not this doctrine, receive him not into your house, neither bid him God speed:
11 For he that biddeth him God speed is partaker of his evil deeds.
KJV
Luke 10:30-37
30 And Jesus answering said, A certain man went down from Jerusalem to Jericho, and fell among thieves, which stripped him of his raiment, and wounded him, and departed, leaving him half dead.
31 And by chance there came down a certain priest that way: and when he saw him, he passed by on the other side.
32 And likewise a Levite, when he was at the place, came and looked on him, and passed by on the other side.
33 But a certain Samaritan, as he journeyed, came where he was: and when he saw him, he had compassion on him,
34 And went to him, and bound up his wounds, pouring in oil and wine, and set him on his own beast, and brought him to an inn, and took care of him.
35 And on the morrow when he departed, he took out two pence, and gave them to the host, and said unto him, Take care of him; and whatsoever thou spendest more, when I come again, I will repay thee.
36 Which now of these three, thinkest thou, was neighbour unto him that fell among the thieves?
37 And he said, He that shewed mercy on him. Then said Jesus unto him, Go, and do thou likewise.
KJV
Some people do not realize (in this parable) that these two first men who passed the beaten man by were actually "obeying" the Law. For they would be considered "unclean" if they did touched this beaten man; therefore, they passed him by in order to obey the Law.
Regarding verse 5:39...it is clear to me that when a person is allowing the evil one to strike his other cheek as well, is when a believer sees an opportunity for the Lord to convict the evil one in his heart. This is nothing about being a punching bag for a husband abuser who is committing a crime.
Just like in the verses that follow...walking twice the distant when one is forced to...to show love. Like, for example, when an unbelieving boss orders you to stay after work for an hour knowing full well that you had plans. And after the hour that you done overtime, you see that the work is still not done and you volunteer to do another hour. The boss sees that you had other plans and he knows that he was taking advantage of you, and he is under conviction that he did not deserve this kindness, but it was given to him without cause. Then he sees the love of Jesus in you, and may be curious why you are so different.
When I look at Matt 5:39, I don't see it as meaning that it means only if someone strikes your face, and you give him the other side.
I see it to mean that we must apply it to our lives when we see it happening. Let's say a man is so mad at a fellow worker that he strikes the fellow worker's property and ruins it or steals it, and the fellow worker sees what is going on and instead of getting mad or madder, he offers him something he owns to make further restitition in what this man apparently thinks he needs to be compensated for. The idea is to bring conviction to the evil one.
I don't see how this can possibly apply to marriage because they both made vows of love when they got married. Actually, Jesus does teach a lot on marriage.
We must take the whole Bible and never single out verses. If things don't add up or seem out of place, it is our fault. We did not interpret the Bible correctly.