I’m a woman and know what you’re saying. You feel like you have to be nice. The way that you can extract yourself without being (too) rude is to kind of unfocus your eyes, look down with your eyes, then away with your head. Try to do it when they’re in the middle of a sentence. You’re immediately distancing yourself and announcing non verbally that you’ve lost interest in the conversation. Then you can do several things…

You’re at a concert, so it’s perfectly okay to say “I really like this band/song. Excuse me.” Then walk away. You’re not being rude, you’re just moving on because you’re no longer interested in the person and convo.

If you can’t really leave your seat, you can look back, sheepishly smile and say “I’m sorry. I’ve had a long day. I’m just going to relax, but thank you for the conversation.” Nurse and stare into your drink/band/phone. Don’t engage again.

This third one comes more naturally to me…if I’m done talking to someone and don’t care if we never speak: “Yeah…okay. Welp, have a good one.” And leave.

If you don’t mind my saying though, if you exchanged numbers with the person it doesn’t seem like you were uncomfortable or trying to get away nicely. I read the post as if you were enjoying the conversation until it caught up to you later. Anyhow, those would be my suggestions to stay courteous but extract yourself from someone’s company.