Responses
His mom had left well before he met Jae-ha. And chapter 10 just explained the drawings were of Jae-ha's mom. So while it is an interesting theory, it is not possible (although if he was going to meet Yeon-ho....the person he has been speaking to on the phone....that I could see).
his friend died wearing adult closes and caring flowers and sketches he was drawing reminded guy about his mom, may be his mother left him cause of that boy? and boy was going on date with her when he got hit by car, than mother left him cause of his friend who died that would be quiet a sad twist though