my boyfriend is constantly liking his exs pictures on ig, facebook, etc.?

[Oni Raptor]

Look, clearly no one clearly explained the rules of dating to you.

\First is that dating is not marriage. You date to meet new and maybe even different types of people. Its like a sampler buffet. Try everything see what you want more of.
If the guy is a jerk then find a new guy.
this whole, "fidelity in dating, we have to make it work," is simply fear or laziness that you will have to start over with someone new.
THE HORROR.

OR
you either accept how a person is and stay or you realize the person isnt what you want to be with and you move to the next table. People are not required to change who they are for you just because you expect them to.

Also he is clearly still attracted to his ex and it would seem several dozen other women on the internet, so is this really the guy you want to be with? Your reaction is normal but you putting up with it seems silly to me.

Oh one edit: this whole "your age, his age" bit. 24/21, same age group. He is in no way an "older man." Seeing how he is acting like he is 12 he hasnt even matured to his natural age yet.