cheating in my dreams

Me and my boyfriend have been ttc for nearly two months but the past couple of weeks I have been having very sexual dreams about him mate. In my dreams I am with my boyfriend and I know it's cheating but I do it anyway. I have to see his mate all the time as he works with him and I didn't fancy him before but now when I see him I just think about my dreams and can't stop thinking about his amazing body which I know he has. I feel so guilty and I would never cheat on my boyfriend in real life. But why am I having these dreams do you think they mean anything?