KIBS….He is seeing someone else!

Hello Dr. Innocent I have this guy that I have been in a serious relationship with for one and a half years. However about a month ago he started cutting off all communication without reason. What hurts more is that I have been told by friends that they have seen him with some other girl several times. My friends say that he even comes to visit this girl at her hostel. I love him so much but I do not know what to do. Please advise.