Alright so I forgotten the title of the manga, but I remember pretty much everything about the novel. So I think it starts off with the MC's sisters friend getting drunk and the MC and the girl having a one night stand. They shrug it off and they go their own way. The girl gets pregnant and has the kid. MC is in like another country not knowing she has given birth to his kid.
Huh... wonder what manga/manhua this is. Reminded me of the novel Hidden Marriage, but plot is a bit different.
I think it's Wangjuede Siyou Baobei. Girl gets drugged by her sister, ends up in ML's bed in a hotel. They have a one night stand, she gives birth to twins.
Wow that's kind of ahhh..... interesting premise, I'm actually interest in the name of this manga/manhua