First off, even if you love her, you have to have a ALPHA mentality..... I mean you could of seriously RUINED your relationship for something as dumb as "she was talking to another guy, at the end of the bar and she didn't introduce me like she usually does"!!!...."" CMON BROOOOOO!!!! ...... MAybe he's a regular and he tips well so she flirts. ALL girls do that in the restaurant/bar industry.... Maybe he's the bf of another girl there, maybe she's making you jealous???? all these are possible, but WHY does it instantly have to go to "SHES FUCKING HIM, or SHE's in LOVE WITH HIM".... Thats a WEAK BETA mind thinking. ITs hard to rid yourself of it, but just be aware of it and you'll be OK....
This simple Mindset almost ruined you cause your following actions were based on your charged emotional state!!! .... You 1) assumed the worst and left the bar!.... Maybe thats why she didn't say bye or asked to go? Think about it. You were pissed on the inside and she feels like your just bailing on her to do something fun. She's gotta defend that EGO and be like "alright, peace out "!!... 2). Your mind went rampant and obsessed over why she's not calling, and yadda yadda then you even talked to her friend to do some reconnaissance work!!!!! thats a big NO NO. If she's a real friend she will eventually tell her what you said.
Anyways bro, your good. BE Alpha and have fun