I tend to get really awful nightmares when I am under stress, in pain from endo, going through an emotionally challenging time either due to health or anything else.
I even got them when I was on anti-depressants to help me sleep due to pain distrubing me.
Was considering talking to a mentor/counsellor just to get it off my chest!
I also had a very frightening experience last year - got beaten up. This causes me sleepless night and bad dreams still.
When I am emotionally upset, my dreams sometimes reflect that but dramatically. Death, murder, war, destruction. Wake up crying and sweating.
Doesn't happen too often thank God. But when it does, I am always weak or useless or ignored in my dream. I choose the wrong times/places/actions. I wake up wanting to correct it all!
I would say that if you're specifially experiencing them after considering the relationship to ask yourself if deep down you have doubts.
Not sure if you feel comfortable with this, but I have in the past found great emotional healing through homeopathy. Did NOT think it would work. But after a course of treatment, my awful emotional baggage was gone. Shame after 4 years I need more but such is life!
Hope this helps you. You're not alone x