Compulsory heterosexuality or just fear of intimacy? (19 F)

I need help because I'm super confused about my orientation and about a specific guy, and I don't know if it's compulsory heterosexuality or just fear of intimacy.

Before I met him, I understood myself as a lesbian. I could always imagine myself in the future with a woman, married, happy, living a life together. When I imagine that, I feel free. When I try to imagine a future with a man, I feel trapped.

Then I met this guy. He's handsome, stylish, smells good, is cool, and respectful. When I saw him for the first time, I felt attraction. We started getting closer, and I got confused. I even told him I was bi because at that moment, I really thought maybe I was.

There were times when I felt really good with him. We held hands, I said I liked him a lot, I felt at peace that day. When I think about his smell, his voice, I feel warmth. It's not repulsion.

But at the same time, every time it starts to get more real, more concrete, I start to feel heavy. It's happened before with another guy: at first, I like it, but when he becomes real, when I see him as a person and things could turn into a real relationship, something in me shuts down.

It's been like that with this one too. Sometimes I think I like him. Sometimes I panic and feel like I never want to see him again. When I imagine continuing with him for months, I feel suffocated. When I imagine distancing myself, I feel sadness and a desire to cry because I'm going to lose him, and he's a good person.

The strongest point is that if I imagine him being a woman, I feel like it would be different. I think I wouldn't be so afraid. I would want to kiss without this block. I wouldn't feel this weight when things got serious.

I keep wondering if this is compulsory heterosexuality, like I like the validation, the idea, but deep down I don't want a man, or if I'm afraid of intimacy and always run away when someone really likes me.

I don't want to hurt him. I don't want to invent an identity just to escape. But I also don't want to continue something romantic if deep down I know I can't see myself with a man.