Why does my boyfriend’s friend (s) lurk my IG?

So my boyfriend and I don’t follow each other on any social media. I’ve noticed a couple of his friends check my IG from time to time. Both have followed me and then when I follow them back they quickly unfollow. I don’t know his friends, I’ve only seen them a couple of times in person. But I’m confused are they just trying to check up on my stuff for my boyfriend or what? Has anyone had something like this happen?
Why does my boyfriend’s friend (s) lurk my IG?
Post Opinion