Does he really like her mom??? Or the mom is dying or something?

he seems really into it. like he's really enjoying having s3x with some old lady T T i think he just likes s3x or been using s3x to survive and came to enjoy it

Upon reading it I think he likes the sadistic side of Suryeon that's why he's enjoying it. I think he's a masochist cause he likes the way Suryeon is choking him and base on the cover photo