When your ex says, "You deserve better" is it BS or healthy communication?

I recently had a loving, conscious, and communicative relationship with a man for a short 6 months. We rushed into a relationship too quickly on the outskirts of his failed engagement. He told me “I love you” almost too quickly, but we both felt it and both wanted to say it.

The very weekend the ex-fiance moved to another state and he reclaimed his place (he had been living with a friend to allow her time to move) he fell apart emotionally and visibly withdrew from me.

A couple of weeks later, we had a mutual breakup that I initiated, but it plagued me that his emotional turmoil so quickly ruined our “honeymoon phase”, which we were both reveling in.

I know sometimes saying, “YDB” is a means of running from intimacy. I am torn between missing him and being grateful that he has recognized his inability to be dedicated to a new relationship at this time.

So my question is for both the rejecter and the rejectee. Does “YDB” sometimes mean “I’m really just not that into you?”

give examples, tell your stories – please help me understand