The older man may not care too much about the way his lady friend feels since she still has sex with him every now and then. But in time, he is going to grow weary of his date's negative attitude and may end the relationship--that is if she doesn't do it first.
When the young woman reaches a point of no return in an age gap relationship, it's not so much that she hates the man she is with, but she is disappointed at the change that has taken place between them. Older men don't remain the same, they age and so do young women.
What use to be fun, unique and interesting a year or more ago may not be anymore for any number of factors between the couple. One would have to sit down with his or her partner to find out what has happened--that is if you still want to be in the relationship.
Nicholl McGuire also contributes to a dating blog here.