relation ship problems

i went to a baseball game alone so i texted a chick i know who goes to almost every game to see if she was there. she was, so i went and sat with her, her friend (same age), and a couple of middle-aged guys that she watches games with often cuz they know everything about baseball. i didnt even sit next to her though.

i told my girlfriend about it and she just said "let me know in advance next time" and then this morning she freaked out, says it's cheating, and wont talk to me.

did i do something wrong?

if you have relationship experience and want to advise me, hit me up at:
iamhumananonymous@gmail.com

thank you

Well, you shouldn't be having relations with ships for starters.