barney:

Yes, this is the million dollar question. What is happening is that she is approaching the problem incorrectly. She is trying to address your sexual needs, which will NOT solve the problem. The only true solution is that she must create the need for sex in herself. (See the His needs Her Needs workbook). You don't need sex, you need a women that needs sex.

It does not matter what the need is in marriage, if one spouse must "Work" at it, eventually the other spouse will basically seek other ways of gewtting that need met, or they will drop that need and increase their resentment.