Fiance texting a friend 'playful message'

So I was being nosey and going through my fiancées phone on thanksgiving when she wasn't around. She had texted this guy that she had never mentioned to me' before a happy thanksgiving message that morning which was normal conversation up until she told him 'you know I love you, you're my sexy pooh bear!' then asked if it would be ok to call him later. I confronted her about it and she's like.. He's married... He's just a friend and I'm gonna call him right now and prove all of this to you... I didn't let her do that but she goes on and says this guy is real comical and makes her laugh a lot when she's feeling down or something... This stuff just really bothers me', what are your thoughts on this?