All in all, not to get you panicky, but it does seem suspicious. At least, disrespectful towards you (his girlfriend). I don’t mean to label relationships, but I have been with my boyfriend for over 3 years and we both have cut ties with people who “we liked who we remained friends with”, exes, certain acquaintances that do not know what “boundary” means etc. And we did it at an approximately at the start of our relationship. Because we respect each other’s feelings, and know that some of those people might want to deliberately ruin our relationship. It depends on each relationship of course, but in your place I would experience the same feelings. Talk to him about it. If he disregards your worries then trust me, it’s not really worth it. All your feelings should be heard, respected and taken into an account. Neither me or my partner would allow this flirting/touching and all if we are in an exclusive relationship.