The lady could be related to MC in other ways, I don't think that's the mom tho. Like I doubt this manhwa has the required spice levels to put MC's mom into this lover-ly hug with ML's big bro.
(And that gave me a semi-depressing idea. Like, if she turns out to be a relative and knows why the mom left. It might be a reason like he didn't want to leave in the first place, was forced to leave behind his kid and partner. Maybe it's like a termal illness cliche where he didn't want to see his child and husband suffer with him, or seeing how ML's family has big money vibes and the pink lady is with them: the mom might've been threatened by his family to leave or something along those lines. I'm reaching so far rn so just ignore this bit, I'm most likely wrong.)
That pink haired lady next to him, is that perhaps MC's mother? Or at least someone on his mother's side of the family?
And I'm still waiting for the father's love story, if we get one. Hopefully yes