Is it possible that my DA ex was more secure before I met him?

My ex was in a LTR for 15 years, 8 out of them their were open. He was with all kinds of women and loved the open thing, except that he got super jealous of his partner being with other men (LOL). Apart from that, he was super loyal to her, they moved in after 3 months, they traveled the world for 1 year, moved houses countless times, had a daughter... It ended dramatically, because of their open thing, but that's not the point right now. He told me that he thought of ending the relationship many times before, even just before he found out she was pregnant. The point is: he never followed through with it, he stayed for 15 years. She's still loyal towards her, on other ways though. But it definitely goes beyond co-parenting.

However, with me he first broke up after 9 months by moving his things out of the house when I was away for half a day and one night. I came back the next morning and all of his stuff was gone. He never did this to his ex. This was only one of about 10 breakups. I did more trips by myself than with him as he dropped out last minute several times. The last breakup happened when we were in Asia and he decided to book a flight back home, but only communicated it with me after, without really seeking a conversation. How did this dude travel with his ex for so many months without leaving her side once?
He had all the DA/FA patterns, to the extreme. Supposedly he had never cheated on his ex, but cheated on me. Is it possible that he developed this pattern as he never fully processed his previous breakup (he cried about her and the loss of his family very frequently for more than 1.5 years of our relationship).