I am a 28 yo guy with MS in a relationship for 10 years now, with a girl that really loves me and I love her, too. I had a similar attitude towards her, but not so harsh. I am afraid of making a family because I feel I am going to be a useless weight on her and my kids' shoulders. I love her though.
I have visited a psychiatrist, was prescribed antidepressants and I cn now see everything much clearer than before. Have a conversation with your boyfriend and see a specialist. He knows better than anybody. Depression is a cunning disease and is associated with MS. A small alteration in the serotonin levels can cause many behavioral defects.
Serotonin is a neurotransmitter of inhibition. Humans are animals, too. If there is no serotonin to inhibit our animal insticts, it results in very weird behavior that, literally, makes no sense at all.
Shortest joke: "We may not be able to cure MS but we can manage its symptoms."