My girlfriend can't stand it when I touch her

Was your gf always this way with you or did her withdrawal develop suddenly?

Also, are there any other changes going on between the two of you in terms of feeling relaxed and at ease with each other, enjoying each other?

Its possible her physical withdrawal, due to her sensitive nature about who touches her and the meaning of touch, reflects an underlying emotional hesitation about her feelings toward you.

This can be either strong positive or negative feelings.

She may be fearful of becoming more intimately attached to you, and withdraws.

She may be actually withdrawing and expresses herself through the amount of touch she wants from others.

Best way forward as almost always in a relationship, is to have a gentle conversation to open up the tension between the two of you.

Sounds like she might be triggered and having a trauma response. This is normal for folks who've experienced trauma. The part of our brains that detects "danger" acts like a smoke alarm in our house: it's constantly scanning for threats and makes a bunch of noise if it detects one. Smoke alarms can't distinguish between smokey bacon cooking or an actual house fire - they just detect a threat and alert everyone of it. Our brain is similar. Her brain has probably learned that physical touch is dangerous for her, so whatever response she has next is her brain's way of trying to protect her. Particularly with sexual trauma, this can be a really frustrating experience for romantic partners trying to connect physically or sexually.