Boyfriend stalking another girl?

I went through my boyfriends followers and saw that he likes all of this girls Instagram photos but doesn't follow her back. The annoying part is that he used to follow her but after I told him I'm not comfortable with them being friends he unfollowed her but yet he's still liking her photos? Does this mean he's stalking her? What's a good way of confronting him about this situation? He doesn't know that I stalked his social media so I don't want it to come up in this way but I'm curious to know what's going on here.