My boyfriend likes other girls’ pictures

Ive previously called him out when I catch him (twice now) where he’ll like another girl’s selfies or in one case some promiscuous photos on instagram, and I’ve told him it makes me feel insecure because these girls just look so different from me, whether its race/ethnicity/hair type, body type (ive been very honest). My boyfriend and I have been together for almost a year now, and I find pictures that he’s liked which are recent, some from a month, two months ago, around my birthday, etc. I just keep finding new photos/selfies that he has liked. A most recent one from three days ago that he hearted on facebook and at this point i’ve told him how I feel, and its embarrassing to keep calling him out because (ill admit) sometimes I fish and look for them (i go through his followers, etc) and I dont want him to know. But what can i do? At this point I want to unrestrict myself from liking other mens’ pictures! Which I know is incredibly toxic because i know it would hurt his feelings if I did it. Which i do not want. When ive communicated hes seemed pretty sincere, he apologized, hes unliked/unfollowed accounts, but again, he keeps doing it! Im just tired of repeating myself with the same issue. I need some advice.