Is it disrespectful to meet another woman while you're on a date?

My best friend went on a date last night and the guy saw his female friend whom he hadn’t seen in a while was also at the bar. He tried to hangout with her too, but my friend didn’t know anybody so felt out of place. The guy told the girl that she’s gotten beautiful, right next to my friend. So we aren’t sure what to make of this. Is it normal for someone say this to the opposite sex while on a date with someone who doesn’t know anyone he is talking to? My friend said she felt really down and distrusting of him, but i wonder if its a rightful judgement.