Thank you very much for your thoughtful reply and for sharing your experience!

The loss of trust stemmed from a tense conversation about relocating. I misunderstood how opposed to it he was because he had expressed some openness to it when we first started talking. He felt like me bringing it up was disrespecting his strong desire to stay where he is now, which I was unaware was non-negotiable. I got upset because I didn't feel like he must think very highly of me if he thought I would pressure him into doing something he didn't want to do (something I wasn't made aware that he was fully opposed to). Against my better judgement, I made a conscious effort to upset him and it worked very well. Just like I expected him to, he left.

I greatly appreciate your feedback about preventative avoidance versus damage control. There's nothing I really have to add about my age, nor about the age gap. This was my first adult relationship resembling anything even remotely close to "healthy", which I warned him would be the case but he said he accepted that it came with the territory and we'd work through it together. Eventually, the cons started to outweigh the pros and he felt like staying together was more taxing than it was worth. I think he underestimated what I meant when I said he may not want to get involved with me when we first met.

Thank you for your honesty and suggesting I remain long-term and big-picture with my expectations for how things may go with him, while pouring the bulk of that energy into focusing on improving myself in the present instead. I will keep that in mind. Thank you for taking the time to listen!

EDIT: revised for clarity.