Hello Javagoat,
While i am not in a relationship, I can relate to your forgetfulness. It has affected my dealings with my family, and just functioning and remembering what I have to do is a challenge. Like those little pieces of paper and notes, and I can't recall the why or who. My son just says I act weird! (He is grown and we don't live together). I suppose that is what he is talking about -- just not being present.
There is a movement on "mindfulness" that you may have heard of. The goal is to be more present in your body instead of living in your head, which I think I tend to do more now since the PTSD. Some are using mindfulness in conjunction with PTSD treatment. There are many books on the subject, but the one my therapist recommended is Dialectical Behavior Therapy Skills Workbook: Practical DBT Exercises for Learning Mindfulness, Interpersonal Effectiveness, Emotion Regulation, & Distress Tolerance (New Harbinger Self-Help Workbook) Matthew McKay, Jeffrey C. Wood, Jeffrey Brantley, Authors.
I can't seem to remember to get the dang book! Perhaps now that I have mentioned it to you, I will. I am sorry you and your partner are going through this. Sometimes, I am glad I just have a goldfish! He does not seem to mind unless I forget to feed him, and then he just quivers. I do get lonely, though, which makes me even more spaced out. I have to make it a point to be around people to stay grounded. Not always easy.
Hang in there,
soulofLC