They had a important relationship in the past. The fact he didn’t remember anything about them is hard to believe and kind of ruin the story to me, specially because 9 years to an adult is not a big thing. If it was 15-20 years would be easier to believe. But he would still know who sungnho was.
If you guys can support the author, her main story is for free at WEBTOON. This couple is so adorable and hot.