Two girls kissed my boyfriend. Idk what to do.

My boyfriend and i are dating for 4.5yrs now. And he recently went abroad for his master's so now automatically it's a long distance relationship. Everthing was good and I was adjusting myself to the new normal.We have 4hrs of time difference but it feels normal bcz he keeps updating me and we talk everyday.But then while being on the vc, he screenshared and I saw a picture of two girls kissing him on his cheeks. I was stunned. And these two girls were his undergraduate college friends. Ik this day bcz he said that he's going to meet his friends and other boys where there too. He said they "suddenly" kissed him on his cheeks and he was too afraid to tell me about it specially before going long distance. He said he's sorry and that he blocked them and he cut all ties with them(which he showed me too) but idk what to do now. He never lied or hide anything from me.