He’s not saying people should not be monogamous; if that works for you, fine. He’s just saying that some people simply aren’t wired that way, and people should recognize that fact.
As far as the “gays don’t love” is concerned: I was once in a public forum that touched on that subject, and a Black woman in the audience pointed out that “homosexuals have sex, but do not love” (and yes, she did that neck thing while she said it). I introduced my partner, the love of my life, then pointed out to her that there was a time when many people thought Blacks were incapable of love, or any other “human” emotion.