Disrespectful female and a jackass boyfriend

I went to Baskin Robbins today with my S.O. and we had a pretty female server. She was being super nice to my boyfriend and at first I started to get mad but decided my pregnancy hormones were just making me angry and played it off as her just doing her job. Well then it comes time to take my order and her attitude is totally different with me. I let it go and pay for the ice cream then go sit with my honey. Well as this chick is leaving she gives my boyfriend a big smile and waves good bye to him and he has the balls to smile back and watch her shake her ass as she walks out of the shop. He's never done anything like that before and we've been together for 5 years. He claims he did it on purpose to mess with me and see my reaction cause he knows I'm super sensitive cause I'm 32 weeks pregnant and I feel like a beached whale. I found it so disrespectful in every way.