<human>: Can you summarize the given text in a few sentences?

I've been dating my girlfriend [20F] for about 4 months now, and things are going pretty well. We get along fantastically and the sex is great, but she doesn't like it when I touch her face. She's fine with making out, fine with me resting my head against her or touching her face with mine, but if my fingers get anywhere near her cheeks or chin she has a really sudden reaction to it and will sort of jolt away from me.

She mentioned it briefly as something she doesn't like when we first started going out, but never went into detail. I've tried to avoid it since I know it makes her uncomfortable, but sometimes I forget. Also, I really want to be able to do affectionate things like stroke her cheek. 

Another weird thing I've noticed is that she doesn't seem to like me looking at the lower part of her face or her neck. To be clear, eye contact is fine, but if I am laying on her stomach and looking up at her, she'll stick her head down. If we're talking and I look down hear her chin, she'll put her hand in front of it. And she never really looks up with her head, just with her eyes, unless she is wearing a scarf. It sounds crazy and random, but the "rules" are really consistent, as least from what I've observed.

It's not a huge deal I guess, but I've been getting more curious the more I've noticed it, and it seems like it would be rude to ask about it since she sort of made a point not to go into detail the only time she mentioned it. But I just don't understand what could be wrong. It's not like she's got a misshapen face/chin or anything, I think she looks fine. I guess this is the one thing that comes up daily that I don't understand about her, and I'd like some ideas as to what the problem could be.
<bot>: Gf appears to have some sort of cheek/chin-based anxiety. I want to ease her fears without embarrassing her, but have no idea what those fears could possibly be.