What up with this girl?

Hey, I need help understanding a situation with a girl I’ve been seeing. We frequently ran into each other at the same place, and we often locked eyes. I noticed her looking at me when I wasn’t looking, which made me more interested. I started going to that place with the intention of confessing my feelings, but I began seeing her less frequently, though I still saw her friend.
One time, I saw her with a boy, but they didn’t seem like a couple. We made eye contact, and I smiled, but I couldn’t bring myself to approach her. Eventually, I checked her social media, found out how much we had in common, and decided to message her.
Later, I saw her in person, approached her, and mentioned my message. She seemed distant and said she didn’t know what I was talking about. After confronting her a third time, she told me she has a boyfriend.
Now, I’m confused about what to do next, but I feel that might have been a sign to back off.
She changed her profile picture a day after I sent her a message, which seemed suspicious since she’s an active Instagram user. I think she posts to seek attention, while I don’t. She's a cat person, which makes me hopeful she’s single. When I saw her, she wore a razor blade necklace, which didn’t suggest happiness. I tend to get attached easily, and it feels like she likes me but causes me emotional pain. I’m unsure if I should try to reconnect, given that she hasn’t responded to my messages or made her account private. Should I reach out again or leave it be if i want her?
Thanks in advance!
What up with this girl?
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