Men equate saying "I love you" with having sex.
Does this mean everytime they're plugging it in, they LOVE that person? I mean, they may be GRATEFUL, which they dang well should, but I don't think this would be LOVE. I mean, I'm a GURL and even I don't equate it 99% of the time, so I can't fathom how a guy can.
If they mean "in a relationship" he shows his "love" through sex and thus equates it that way, that's crap. Grow a spine, open your mouth and SAY it.
Of course, being that I write romance, this could particular irk me. As writers, we work really hard to have ANYTHING, from words to actions, reflect the movement in a relationship. To that point, yes, often times if you do choose to have a sex scene, and since it does need to have relevence in the book, it can mean that, but I refuse to acknowledge that because then Cosmo is at least partially right.
Then again, I write heros with spines. That's one of the things that makes him a hero, after all.