Lucretius is supportive of sex as a way to satisfy the claims of the body, but he is critical of romantic love. I'll be at more liberty to comment when I get home from work.
The mores of the time of ancient Greece were such that prostitutes were legal and were taxed. So if a man developed a romantic attachment to a prostitute it would lead to problems, since he could never be assured of her love (as she would have other clients, and perhaps was pitting him to try to make him jealous).