Girlfriends not allowed at jam

I'm a guitarist/vocalist of our band and for the first time our bassists girlfriend was at our jam hanging out.

We did our full set and she started off by saying I was really good and asked if I had vocal lessons. I was only being honest and said I'm self taught and I play guitar mostly by ear.

Out of nowhere she gets all confrontational and says I'm full of myself and have a massive ego. I responded with "im a musician we all have massive egos" and my band mates Chuckled. She proceeded to get mad and accused me of one-upping her boyfriend and that I acted like I was "better than him" to which I responded "we've been playing for 5 years now, this isn't an issue". He then tried calming her down and told her to stop. She said she wasn't trying to start anything but I called her out on her bs and then she went back to praising me again.

She also had like 4-5 beers in under an hour so this was mostly manufactured drama.

I ignored her for the rest of the night but damn now I understand in the music world when people say no girlfriends allowed at band practice.

Anybody else experience something like this?