On the webtoons app, but you first have to change the language to Chinese. Manga name is called 甜蜜婚礼.
Here's the online site
https://m.webtoons.com/zh-hant/romance/honeywedding/list?title_no=1207&page=1&webtoon-platform-redirect=true
Is she child of her father's affair or what ?
What? No no no, she's not hahah. Her real parents are both gone, her father now is actually her real dads brother.
Oh thanks. so why her uncle's wife hate her?
Jealous envy and such. I've just reread it lol, so the aunt dislikes all those people who can smile so happily, especially when she sees how much MC real mother was pampered by her husband but the aunts own husband was only focused on his work and neither hot or cold towards her.
May I know why he married her?
Oh wow, I didn't know this was here, no wonder it looked familiar. Guess it's not going to be updated. Anyway, I've read the original version and the Chinese raws of it, definitely would recommend! I think it's already completed??
Plot- our main girl ends up getting in an arranged marriage with male lead, who's also her teacher. It is a bussines marriage, she lives with her dad and stepmom(evil) and elder sister.
Anyway, she proposes a contract marriage to the male lead because she wanted freedom in highschool. There is a time skip and the real story starts when the male lead comes back from abroad and she's in uni! *-*
After you get over the initial drama, their married life is so sweet! Because there is a story to why the male lead agreed to the marriage in the first place