I like this trope of love feeling “earned” & right when it finally comes too but surprisingly can’t think of many examples. My absolute favorite that this trope revolves around is actually Pacey & Joey in Dawson’s Creek but that’s not what’s being asked for.
I def second The Story of Minglan. Although it does have a ton of episodes the romance really is full and their story is really complex and complete, as both individuals and a couple. It’s one of those where you really get that meant to be feeling even if it’s not portrayed as such (bc it doesn’t have to be). This is ultimately a story of growth and love of all kinds though so while it is centered around the main couple as individuals & a couple it still features a ton of different amazing characters as not purely a romance.
I think a lot of the cross dressing dramas feature this trope (not all equally well but u know) like Coffee Prince & Sungkyunkwan Scandal, wherein the leads spend a lot of time together so you understand why they fell for each other without initial interest. I do think the time they fell was rly close though so I’m not sure it features enough of that ‘male lead falls first’ distinction you want.
I would recommend Go Ahead but then again he does fall super quickly. It doesn’t feel reasonless or unearned so you might still enjoy it.
Maybe My Princess & Marriage, Not Dating too. I’m not sure how much of a distinction in time you want between how the leads fall so they might not completely fit.
Also I def +1 Glorious Day, male lead def falls first & it happens after time spent together but not like an excessive amount.