I appreciate everyone's thoughts. Lexie - I hear what you're saying loud and clear. I was previously in a relationship with a man for three years - not an A, by any stretch. Lovely guy all around. I thought for sure that we would get married. We lived together, too. One day I woke up and realized that I was profoundly unhappy, unfulfilled, and bored. It's not that he did anything, necessarily- like I said, he's a great guy. It was just that we weren't a good fit for each other.
Point being, I know that relationships, with or without an A, can end for that reason. You're right that I should be cognizant of that in this situation.