I dunno I have a hard time believing Ethan was abusive to Mark. I can easily see how he could've grown to resent Mark, and lashed out but not anymore than anyone else who has fallen out of love with someone.
The way i saw it is that Mark and Ethan's relationship was awesome when Ethan was following Mark's lead, but when the dynamic shifted it kinda went to shit. There are so many old videos where Ethan was annoyed when Mark would try to film him or purposely moved out of the way of shots. It was around that same time that Ethan started to post himself with lipstick on, and clearly was trying to explore himself in a nontraditional masculine way.... which is very opposite Mark's frat bro with a video cam who happens to be gay brand.
Ethan also initiated both breakups. Mark couldn't get a clue, and cornered him back into the relationship. It was obvious back then that Ethan fell out of love with Mark pretty soon after they moved to L.A. Even during their first breakup video, Mark kept saying that this was a needed break, but Ethan's body language was not having it. There were so many comments left on various videos where people either assumed they'd broken up or were thinking they were headed that way.
Anyways, I sympathize with Mark, it's not easy being the person that gets dumped. He genuinely seems like the type of person that loves hard, but the whole relationship was always Mark attempting to make Ethan a bro type gay when Ethan has always been a more feminine artsy studious type. The only reason anyone is surprised that Ethan did a 180 is because we were all seeing Ethan the way Mark wanted us to see him. So i hope Mark isn't delusional enough to think that he was being abused.

I like him more than Ethan, but that's a damn lie.