Idek what to do

So I’ve been talking to this guy for some weeks and he made it completely clear to me that he wanted to date me and he didn’t want anyone else so I was lurking I know I shouldn’t be but I was looking and saw that he liked other girls pictures and idk it made me feel some type of way they’re beautiful girls and more his type which makes me feel insecure but I don’t want to tell him anything because he might be like wtf why were u stalking my page or something. Idk should I just not get my hopes up anymore I always make time to see him whenever he wants to see me I say yes I text him quick I do everything good I just don’t get why every guy I’m with still try to talk to other girls n stuff.. I try not to act jealous but I lowkey am. Also he says I could hang out with whatever guy I want to go with so Idek what to think. Should I just block him or slowly back off or is there anything I can do to get him thinking and want me more or something 🥺 I’m 19 btw n he’s 23 he also always says he’s scared to get cheated on again but I would never do that.!

Update: he had told me once that if were not going to try to date then he doesn’t want nothing not even friendship