My girlfriend [24F] cut her hair short and now we look like siblings. I [27M] am completely turned off. She says I'll "get used to it." I don't think I will.

This is a bizarre and embarrassing problem, which is why I'm here instead of consulting friends.
My girlfriend and I have been dating for 2 and a half years. Throughout our entire relationship she has experimented a lot with her hair. Naturally she's a blonde but she has dyed it many colors and sported a lot of cuts. About a month ago she was toying with the idea of getting a short haircut. She's never had short hair before and was sort of concerned about my attraction levels. I'll admit I've never been a huge fan of short hair on girls but I love my girlfriend very much and was sure my attraction would not be entirely dependent on her hair. So she got her hair cut and also dyed it a dark brown.
When I first saw her I was shocked. She literally looks like my sister. In the past people have commented that we do kinda look alike, but I never really saw it. I mean, we're both white, brown eyes...but I just never thought we looked alike.
But now...she looks like the female me. With the brown hair and short cut she literally looks like me if I was a chick. It's all I can see when I look at her. It also doesn't help that she really didn't get a feminine short cut. I don't know a lot about hair but it's not like your usual girl's cut. It looks like guy hair.
I gave it a bit of time to see if I got used to it but I didn't. My girlfriend noticed I wasn't initiating intimacy as often as usual and asked me about it, so I told her the truth. She laughed and said I was being ridiculous, that I just needed time to get used to it after seeing her with long hair for so long. I agreed and said she was probably right.
Well, last week she made an appointment to get a hair cut. It's been a month with the short hair and I still feel no sexual attraction to her whatsoever. It's honestly so bizarre but I can't get passed the fact that she literally looks like me. I begged her to not get her hair cut and grow it out, at least enough to get it styled differently. She got mad and said I couldn't tell her what to do with her own body and went to get her hair cut.
I don't know where to go from here. She's right, I can't tell her what to do with her body. But I can't even imagine having sex with her. I still love my girlfriend so, so much. I don't want to break up. But I also think sexual attraction is important and right now that's nonexistent. What do I do?
TL;DR: My girlfriend got a short hair cut and looks like she could be my sister. I feel no sexual attraction. What do I do?


Source.