Ok guys, I would just like to get some perspective. I was at a bar with my girlfriend one late afternoon. We had a cocktail and an appetizer, nothing unusual. We had two younger, good looking male bartenders waiting on us whom my gf struck up a conversation with. So we're all talking, she's all over me btw, taking selfies and being the doting girlfriend. We get the tab, as we had someplace we had to be, and I sign it leaving 25% tip (which I asked her if it was enough).

Now, before I go further let me say that my gf (30 years old) is very outgoing, bubbly, attractive and likes attention. She's the type of person who can have a conversation with a brick wall, but she would prefer that wall to be a hot guy.

Ok, so I get up to use the restroom leaving her and the unclaimed check at the bar...When I come back i saw that my gf had taken 8 extra dollars and put it in with my tab and had moved the check presenter off of the bar onto the cooler that sits below the bar. But by virtue of the fact that it hadn't been taken, the bartender was not the one who moved it. My gf obviously moved it so that I wouldn't see she had stuffed money in there.

So I called her out on it and said that what she did wasn't cool but I didn't outright accuse her of padding their tip because she thought they were "hot". But that exactly what I feel she did.

To me this is insulting and disingenuous. I feel like I couldn't trust her in situations where she's out with her girlfriends. What would you do?

Edit: the signed check sat in front of the two of us for ten minutes during which time she could have offered the cash. But it was when I was out of the room that she added it. Covertly.