So to start this out when me and my girlfriend started going out last may we were both casually dating and she went on a date with her gym trainer. well after my girlfriend and i became official he texted her saying not to say anything because he didn't want to get in trouble, cuz he could lose his job. he also invited her out to drinks with other people from her fitness boot camp but my girlfriend said no because she wouldn't like it if it was the other way around. well over winter break i was laying on the couch with her and saw that she got a text message from him seeing how she was doing and when she was going to be in the gym again.. well not 2 weeks later i saw that she texted him i miss your face =) and he responded i miss you too.. well i feel because they have been on a date before that it is wrong for her to text another guy saying stuff like that.. am i being overly jealous? what should i do?