this pattern is very similar to what i just experienced! i'm just gonna word vomit and maybe something will click.
the first two break ups, he was afraid of you leaving him. just my guess.the last break up, i'd wager, he had convinced himself that you would leave him so he started shacking up with his friend. not staying at his house is the 'nice' rationale he can use to tell people why you two broke up.
its all remarkably similar to my own experience - right after she told me she wanted me to be her BF and someday, best friend, she started becoming more impacted by the distance. started looking for things to get upset about, kept repeating fears regarding the distance and time apart and that when we were together, she wasn't able to be as productive... eventually we made some changes, through the advice she got from her therapist, to make the distance and time apart seem smaller. then, right before our trip, she started trying to get me to fight her over small things. she knew i needed to sleep early, yet she would keep me up on the phone, trying to get me to chase my tail - but i wouldn't hang up 'angry' because i was still in the 'keep the relationship afloat!' mindset. she tried again, on the trip, where eventually i just told her 'i never want to break up with you'. things were super lovey-dovey after the trip, but she was spending a lot more time with her (only) local friend - a now-single losery guy who was always available to pay attention to her - and less / less with me. she eventually just called and ended it one day, after being the exact same even that morning. gave me the same types of easily-overcome excuses that you've listed. i didnt argue on the break-up phone call, but certain things she said more or less confirmed that she had moved onto this 'new favorite person' at least emotionally and was clearing the way by dumping me. it was weird, she sent a text later saying she loved me but wasnt sure i was the one... yet if she scrolled up 10 messages she'd see her hourly affirmations of appreciation and love for me from the day before! i was pretty messed up for awhile but when i started finally opening up about all these strange details to friends, i circled back around to her mental health issues and all the reasons why she wasn't ready for the relatonship I thought we were building. i definitely spent the next month or so periodically sending messages, both angry and hopeful, to try and at least get an explanation for what happened. i would go between blaming her for the way i had become to making sure she felt like she still had a place to run.
then, i started reading about Borderline Personality Disorder, and Cluster B. I did a deep dive on r/relationships and r/bpdlovedones etc. a lot of the stories hit home. not to play doctor, but i would be curious to know if there were maybe a ton of other subtle things that you looked past because you felt the relationship was strong. i have come to the conclusion that there are nefarious BPD people and truly self-defeating ones. but many seem to bounce between the two - even if therapy, medication, structure, and nutritional routines.
give yourself time and think of this as a dead relationship for a moment. then, start allowing yourself to think about and talk to friends about all the little things he did that were off over the course of the 9 months. journaling helps. the floodgates will open when you do this and you may not want to see him any less.... but your brain will start the process of accepting that you are 10000x better off without having to exhaust yourself with someone elses problems. i imagine that youve lost a lot of your own personal stability and aspirations over the course of the 9 months. shift back to these things!