Thank you very much for your comments. I would want to make
a sharp distinction between four quite different experiences:
What Jesus said in Matthew 5:28 was that a decision to commit adultery, even if one does not get to do it, is already adulterous. That is experience c.
He did not say that finding others attractive is sinful, and in fact He was the one who designed us to appreciate the beauty of others - Colossians 1:16. As Son of Man he must have found the women who became his disciples very attractive - Matthew 27:55-56. He was also tempted in all points as we are (and that must have included being tempted to immorality) - see Hebrews 2:17; 4:15.
It therefore seems to me that a Christian woman should not be surprised if her husband notices and appreciates other women. There is no point in praying that he will not be tempted, since that is inevitable. She should rather pray that he will be empowered by the Spirit to love his wife and be totally faithful to her - Ephesians 5:28. And, let's face it, without the power of the Holy Spirit very few men, or women, are truly faithful.
That is why I feel that focusing our prayers on the mighty power of the Holy Spirit that raised Jesus from the dead - Romans 8:11 - is far more productive than trying to keep one's partner from noticing the beauty of others.