AITA - Guy bought my gf drinks all night

Gf was out with her girl mate last weekend. They were just having a quiet one, bit of food then she was going to drive home.

She bumped into a guy who she previously has said fancies her.

Gets drunk, stays out till 1am and ends up staying on her mates sofa rather than going home.

Tells me the next day that this guy was buying her drinks all night.

I trust her but also feel a bit disrespected.

AITA for feeling a bit off about this?