Agreed that we should always have our spouse's best interests at heart..... but what happens if what we think is in our spouse's best interests is not something that they think is in their best interest? It gets messy.
I think (and I could be wrong, but I seriously doubt it) that when two people have the Holy Spirit residing in them, and this Spirit of love is clearly evident to the other, then this is the guiding force.
For instance, what woman, upon seeing, hearing, and feeling the Spirit of Christ in her busband, would not respond to that love? And what man, observing the Spirit of Christ in his wife, would not love such a woman?
Perhaps this is too simplistic, but sometimes I think the answers to complex questions are quite simple.