In my case two things helped:

• during one of our crisis, we decided to have a "pause" in the relationship. During that time I realized that I missed her, and that her absence evoked pretty strong emotions in me, indicating that I had "feelings" for her (call it love or whatever).
• after a couple of years of relationship, I could recognize that it was still healthy, which gave me more confidence for the future, and an interest in moving forward with the relationship