So, a few things.
First and foremost, his friend is kind of an asshole. Guys do tend to take shots and make fun of each other, but that was not the time. Not to mention he was apparently snooping through the MC's phone at some point? Not cool.
Secondly, judging by what she said when she saw him, she either knew his father at some point (possibly) OR he looks like someone that she used to know (and maybe date?). MC is WAY too serious too.
Lastly, I wonder why she wants to keep her being a former gal a secret.