I keep having really vivid dreams of my partner cheating on me, why?

I have no definitive answer for you, but I do have a blog where I've written several articles on this very subject. You can go here and find them if you wish:
http://travelguy.typepad.com/dreams

Hope this will bring you peace about this,
John

i wanan knoe dee exact same fing bwoii..
soo u finkk i shuld get high ery night?

If an actual lover is the one being UNFAITHFUL, then this indicates the dreamer's insecurities over the relationship. The partner may or may not actually be UNFAITHFUL, but either way the dreamer needs to deal with her feelings.

Insecurity on your part is the problem.

beacuse you love him or her so much that you feel that the only why they can get out of our life is by cheating beacuse you feel like nothing else would hurt you more then him or her finding someone else so you subcontisness is screaming to you that it bothers you on a daily bascies and think even though its just a dream it will tare you apart from each other and make you fight more beacuse your scared of it happening that when you wake up it feels so real you should talk to him or her and let them know that your scared that it might happen and that it hurts you so they can help you understand they love you the same but do it befor it tares you apart or they do it beacuse you accuse them for it dont let it get to you so much i used to to but then we talked and i felt better after every dream or you feel like you dont have enough sex in your realtionship that your subcontisness is telling you if you dont this might happen or your sexually fustrated

It means nothing. Its just a dream. Stop trying to enquire about something that DiD nOt and WiLl not hApPeN.

either you want to catch him so bad, you only think of that. or you are so scared that you may actually find out he;s cheating, that you only think of that.
Anyway, dreams are only "replays" of your thoughts, and they have no other "meaning" than psychological .