Don't prosecute spousal rape, she was wearing a nightie.

[kılıç_mehmet]

I mean, if you don't want to sleep with your husband/wife, why not get a divorce in the first place?

Rape is defined as putting any object into a bodily orifice withouth the "owner's" consent. So what if someone gives you surprise buttsex, or is otherwise abusive and decides that it's a fun idea to fuck you with a broom? Just because you (occasionally) want to have sex with your spouse, it doesn't (necessarily) include these two examples.

I mean, why would a husband need to rape his wife?
It just doesn't make sense.

Why does ANY man feel the need to rape a woman?

Well, that is a completely different phenomena.
As you probably know, the issue of "consent" nearly entirely revolves around women. Meaning, women are able to have sex whenever they want to, however, men must always seek the consent of the female to do so.
This is also true in nature. So whenever a man decides that he is being left out, and has no money to pay a prostitute, some become more desperate and resort to this. Some may have fetishes involving this and may simply indulge in it for a specific pleasure.