So my fiancé and I live together in an apartment and our neighbors fight a lot. When they fight badly we can hear them. Well my fiancé messaged the girl on Facebook and asked if everything was okay. Which was fine but after that they became friends on Facebook. I asked him multiple times to please delete her but he never did and told me he just wanted me to trust him. Then I kept catching her watch him. She would be looking out her window when he was outside and sometimes she would go outside to. Then I found out he had blocked her on Instagram and he hadn’t said anything about it. Well a few days later she followed him on a different account and he followed back. Then she went back and liked pictures from before we were together (almost two years ago). I looked on the account and her boyfriend didn’t even follow her on it. So I talked to her boyfriend and he told me they had messaged two other times. She told him sorry because they were being loud again. And then he messaged her and told her that his phone had messed up and kept sending her friend requests and said he was sorry. I got mad that he didn’t tell me this stuff because I asked him over and over if there was anything else because it was a weird situation. He swore up and down that nothing else had happened and the only reason he didn’t want me to know about it was because he didn’t want me mad. But every time I asked he always said “no I only messaged her the one time that you saw” which was a lie. Should I believe him that nothing happened? Or should I be worried? Ever since I found out I feel like I can’t trust him.