You are assuming, it seems to me that she is being intamate with someone else. You do not have proof do you? If there is no proof maybe she is staying with a friend because she does not feel wanted by you and needs the space. Maybe she sleeps on the other side of the bed bacause she feels rejected but, won't say anything.
The road can go both ways. I think you both need to say just what you feel. With out a discussion and speaking honestly about this I don't see how you can move forward. Believe me youv'e read my post and have seen what no communication does to a M and you, yourself have told me this.(which I very much appreciate.)
JAK
You don't get to choose how you're going to die. Or when, you can only decide how you're going to live now. ~Joan Baez