You do not trust him. Otherwise you wouldn't be asking this on here.
He also, does not see a long term future with you. If a guy is really in to and wants to make your relationship something true and honest then he wouldn't be liking other girls that are provocatively dressed etc. He wouldn't feel the need to. It's a simple as that.
Either he's a guy with no respect for you or he's not mature enough for a real relationship yet. Sure, he maybe ready for the physical side of seeeing either, showing love. But the mental part of putting you before him, supporting you and making you feel valued. No, he's not ready for that. Accept he'll eventually cheat on you and enjoy your time together, or, find another guy.
It doesn't have to be the first guy that shows interest either. They're usually the ones hoping you'll be on the rebound. Take some time for yourself and don't settle for anyone that makes you feel this way.