How can I ask my boyfriend about a girl he just followed on Instagram without appearing controlling?

Anonymous
Hey,
Please don't get me wrong. We have a good relationship, I trust him. There is one detail i needed to address: He's not a social media guy, nor he posts or follows randomly. Mostly he uses Instagram to follow work related accounts, and people from work/his clients he hangs out with. I know them all. About 3 weeks ago he followed a girl, who does not seem related to any of his followers, also he has not shared anything about her with me. She looks like a normal person, not a celebrity, and I might be subjective, but she looks attractive. Just out of curiosity, though I never felt the need to ask about his followers before, I feel curious of her. I want to ask to my boyfriend, but I don't know how. Don't want to appear controlling, even though I like checking his activity sometimes, to myself.
Can you suggest me how can I ask about her? What can I say (not say)?
Updates
1 y
P. S. The girl is not following him back, though.
How can I ask my boyfriend about a girl he just followed on Instagram without appearing controlling?
3 Opinion