Why do I keep alternating from liking to hating someone??

(English isn't my first language! Sorry if some stuff don't make sense)

This is really bugging me. When I meet someone new and get really close to them, for the first few months I start to idolise then in my mind, they're my new favourite person and I try to talk to them frequently/daily, and I don't have ANY bad opinions about them. Anyways, for no reason one day I just begin to dislike them and everything that they do (that used to not bug me at all) now annoys me and irritates me to my core.

My most recent example is one of my 'new' friends, let's call her A (wouldn't call her new but only this year-last year I've started to get closer to her). She's not even a bad or dislikeable person, and is fairly mature in my opinion. We'd used to talk for hours privately daily, and I really loved her as a friend. Never hated her, had no problems with her whatsoever until ≈2 months ago. I'm not even sure what started it but I just began disliking her for no reason.

Anything that reminds me of her even if I'm in a good mood makes me feel irritated, and I try to avoid it as much as possible. Now I don't always dislike her, if I'm in a very good and happy mood she's nice to talk to and I start to question why I've begun to dislike her in the first place. But when I'm in a neutral or bad mood, it feels like whatever she does will atleast get a little bit on my nerves and tick me off even more. Even if she's not talking to me or isn't being rude to me at all.

Also, sometimes I start to dislike all of my friends for no reason it seems like. I become very irritable and start to ignore and dislike everyone near me. This usually happens every few weeks and might last anywhere from a few hours to a few days. I'm currently experiencing this right now and the people that for some reason I dislike with no reason get on my nerves even more than usual or start my whole horrible mood, even if it's unintentional.

I'm so confused on why this stuff keeps happening to me, also if it wasn't obvious already I'm a teen girl so does that explain anything :,) ?? I do have regular moodswings and I consider it as normal but I'm not sure if this is. Am I just overthinking it?