Some people get nervous and fidgety when they are on camera. I sometimes talk to family on skype and we will use the webcam sometimes and as soon as it is on I stiffen up or start fidgiting and get awkward, which is very different than how I am in person. It sounds like Greg loves you very much. Distance can put some stress on a relationship, because it's hard being away from the person you love and it increases anxiety. Maybe next time you feel like accusing Greg count to ten and take a deep breath, list all the things you love about him and wether or not there is any proof he is actually doing the things you want to accuse him of. It sounds like Greg loves you very much and wouldn't betray you like that.