I have the same situation with my boyfriend, he's a poly i'm a mono. We have an amazing relationship and he says he wants to marry me and sees us together for the rest of our lives. I have been very insecure and jealous lately because he moved to a different state for work reasons and we have to be apart for a while. We are trying to see each other every month and so far it has happened, but he has already had 2 relationships. This is the first time since we started exclusively (10 months) that he has been with anyone else. This is all very new for me and I love him so much I don't want to loose him but sometimes I wonder.
I thank everyone in this thread because you have been very helpful. All the comments and advice I can get are really appreciated