It is tough. Can you ever really tell if the problem is your mental state stressing out your relationship vs your relationship exacerbating your mental state?

For me, the roughest patches in my relationship have been causes by my own mental instabilities in most cases, and my partner's issues in only a few. When we've weathered the storm so to speak, I have been thankful I didn't act while in the depths of depression or whatever emotional issue had come up.

However, there are many people out there who are in relationships that exacerbate mental health issues. It is incredibly hard to gain enough perspective to be 100% sure until you take action. It might help to journal some of your thoughts, and then review them after a period of time to see if your relationship is one of the sources of your stress and frustration or if it is just a victim of the stress and frustration you are feeling. Discussing with a counselor may also help gain clarity.

Hang in there! Things WILL get better, and you WILL be able to choose the right path for you!