I need advice....

I’ve told my boyfriend plenty of times that I take A LOT of offense to him hearting girls pics on social media. Now this may sound petty but what I’ve noticed is the girls who pictures he hearts are the ones who heart his. In his mind he’s “showing love” back to their page since they showed love to his. But the reason I’ve also made this a big deal is because on Instagram he even took it as far DM’ing one girl saying “you are soooo gorgeous” and sent hearts to another girls DM as well. I’ve expressed how It makes me feel and he has continued to do it. Caught him doing it today. I don’t like it at all.......... How should I handle this? Cause at this point I’m tired of repeating myself