Oh you deserve so much better than him. In just a few short posts, you've told us that
- he rarely complements you
- he goes out of his way to tell you how attractive he finds other women
- he especially seems to like young women (ew)
- he goes out of his way to tell you someone else fancies him (that could well be made up by the way)
- he agrees not to add someone as a friend on fb (because she's made it known she fancies him) then adds her anyway.
What you seem to have here is someone who WANTS you to feel insecure. He makes it clear he finds other women more attractive, and they find him attractive. ie he could leave for someone else at any moment if he wanted to.
He doesn't necessarily genuinely think that, by the way - this could just be a manipulation to keep you in your place. But whatever his reasons you deserve better.
Either he genuinely fancies loads of women, especially young ones - and doesn't mind telling you that.
Or - he is making some of it up to make you insecure.
He sounds vile. You will be much better off without him. I would tell him it's over. Don't feel the need to explain why - just say it wasn't working for you. That way he can't argue with your reasoning. Please don't be tempted to stay with him just because 'he's less bad than previous relationships'. You know that isn't a good reason.
If you want a r'ship (one with a decent, respectful, kind man) there is plenty of time to find one. Every month you stay with this loser reduces that time of course.