6. Because he knows talking about it will lead to trouble.
“Even if we sat down and talked about it, I’d never be able to convince her to break up with me.”
We can see that the girlfriend in question is quite a handful. The guy might think, “I just know she’ll go berserk, so I can’t tell her that I want to break up even though I want to. Staying together and breaking up would be equally bad.” Even though she would disagree, the fact of the matter is that they must never have been compatible to begin with.