I swear that i read the a manga with the exact plot like this one but the difference is the reason why the guy only date for 7 days, if i'm not wrong in the story im looking for is there's a jealous ex who spreading a rumor that the guy will only date girl for 7 days, so all his girlfriend end their relationship with him exactly after 7 day.
So cute, exactly like the father
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcR6Fp0S4Lv668zcptGPkA6zbX5_32IW7mo7Ww&usqp=CAU