hi,
the first question to get out of the way ,which is an obvious one,,are you truly happy in your current relationship?
if not,then this dream may be compensating for the lack of something in this relationship,
how do you feel about what you are doing in the dream ?,
if you are in a happy relationship,the dream may still be compensating you ,by showing you what it would be like with others,in effect to help you realize & appreciate what you already have.
sorry if this all sounds a bit mundane & therapy like,need to start somewhere.
hope this helps,
rgds mike