That is a really good point but it looks like they're using Kakao, if one of them got a new number then you make a new account I think. Or Gunjoon might have just read those messages got embarrassed and deleted everything, who knows.
it looks lkke he changed his number when he got a new phone, his phone here looks like an Ultra while the phone he has now is a Z Flip
i think sometimes he changed his number after some bad breakups, and there's a high chance he did just that
Okay but then wouldn't he have those texts in his phone and seen them when they reconnected..?