Question about visiting Ukraine, random life decisions, and kind of a vent

I (26F) am considering/planning to visit in the near future. I'm going to visit my friend (well, more than a friend but I digress**). From my understanding from what I have read and asked, with a short term type of visa, I can stay up to 90 days within a period of 180 days. Is there another way that I could reasonably stay for a slightly longer time period and what would this require? I'm an American citizen (but have dual citizenship with another country as well).

** For context:

The Ukrainian "friend" I am intending to visit (28M) is more than a friend but it's difficult to articulate. He previously also lived in California where I live but decided to return home in the middle of 2022 because his parents and the vast majority of his family are still in Ukraine. In a nutshell, he said he couldn't in good conscience just continue here as if there wasn't a war. While he lived here, we were just friends and we did continue speaking even after he left. In June of last year, I visited him for a short time and we got more than friendly. Even with this, I was still not entirely sure of wanting to be more than friends and I got the same vibe from him at the time but in the past 3-4 months, that's changed. Over Christmas, he asked what I've been up to. I mentioned that I'm taking a break from work for the next couple of months since I'm tired of my job setting (I'm a PA/Physician's Assistant) and finally quit in order to do something different and he brought up visiting.

In regards to the above my close friend (here) brought up something that I didn't really consider. She said to me that 3+ months is a long time to spend with someone and that he's going to get used to my presence and I can't *legally* stay longer than that and he can't leave, so I'm just making it difficult for him and I, I guess.

I would appreciate any comment on that as well.

Thank you for reading my scattered rant.