My boyfriend of two years whom I very much do want to stay with has come out as bi.   Initially I found about an interaction between him and men which he claimed was purely just that and nothing else.   He has had others as well.   I have struggled very much over the last year since finding this pits.  He claims he only wants a relationship with me , a female.  That these interactions mean nothing.  This is hard for me to grasp.   I am the only person in his life that knows this about him.   He has had a troubled life and bad divorce … he feels like this is a part of him that he wishes to at least act on from time to time . The latest is development is that he would like to be able to have occasional )once monthly) interactions with men.  That he will notify me when this happens and we have clear boundaries set.  I have told him I’m ok with it but I struggle every day because I do not want to lose him.
I am hopeful he will keep his word and be honest and let me know when it happens… so far I do not know of any interaction since we made this agreement.   He is on meds and will use protection as well.   
Since all this came to light I will say he has come out of his shell.. his walls our down and we are stronger in some ways.  He sees us in a long term relationship.  We live together… and I have my kids part time as well and they all have a great relationship with him.
I need some help in coping and would like to know if any of you are in a similar situation.  Thanks