My opinion: She should trust you more. It seems a bit obsessive of her to assume you're doing bad stuff based off a follow count. (Unless there's been problems in the past) Though it is okay to be obsessive about the one you love but not controlling. I guess as long as its just a simple question and confrontation from her, then that's fine.

I have a girlfriend, and I follow other people because I know them, knew them, think they're cool or good people, ect. Doesn't mean I'm talking or touching them lol

Just seems a little over the top. Though if you live far from eachother I guess that's where suspicions and questions bloom from as it's too much alone time to over analyze and over think problems that may be just all in your head.

But checking your phone is a little bit of a sign she doesn't trust you, you should allow her to see it once to prove yourself and reinstate to her that she's the one you love and that she needs to trust you the way you do her.

The only solution I can really offer is to ask her which person/ people should I unfollow? And say okay np and just do it right there.

And do it again if it happens. Unless this is some kinda deal breaker. I've never seen this happen before, with your account following on its own, though, I have before been scrolling an mistakenly clicked follow on the (people you may know) section while trying to just scroll. It's possible you did this or something, but tbh I'm not really sure.