My (25F) ex (23M) became completely cold after our breakup, could this be fearful-avoidant deactivation?

My ex(23M)broke up with me (25F) out of the blue saying he wants to work on himself, we were together for 1 year and 7 months, he said that he lost feelings, the change in him happened the day after he was meant to tell his dad about marrying me, he was nervous about marriage and even went to the point where he threw up. He started being distant the day after, barely messaged and the breakup happened 3 days later. He said he lost feelings 2/3 weeks ago but that was around the time he was meant to tell his dad about us but cause of anxiety he kept delaying it, he was also anxious and stressed about things going wrong in his life and was about to loose his job, we did have a lot of arguments that month too, which he later mentioned he became numb with his feelings everytime we argued so he's convinced that's when he lost it.

people with fearful-avoidant attachment, can deactivation make them suddenly act extremely dry, cold, distant and almost like they don't care after a breakup, even if they were loving/affectionate before? Can they genuinely feel numb and convinced their feelings are gone, then later soften or realise they were emotionally shut down? And what triggers it ?