You know what my problem with Yahari Ore no Seishun Love Come wa Machigatteiru is? It's been so long that I've completely forgotten about it except for very few key plot points and it makes it impossible for me to start watching season 2 because I can't enjoy it that way. Kinda sucks. :/
You know what problem you'll have with your preferences? It's that very few SoL romances have a happy ending. Most are just open-ended or want you to start reading the manga that's been going on for years already and the anime was just to get you hooked.
I'd be interested in knowing if you only want "realistic" settings. There are many great SoL romance comedies but if you want to have a realistic school setting then most are going to feel the same: uninspired stereotypes, same old harem settings and rarely a happy ending.
There are tons however that incorporate some other element: Maybe people have superpowers in one anime or the protagonist finds himself with a girl as his hand (
Midori no Hibi, I feel like that'd be right up your alley! Happy ending, very unique, check it out!)
Or if the main genre has to be romance then you could start looking at Shoujo shows (anime catered to girls that is) because they like to do romances with realistic settings and they have characters with depth or try to be refreshing (my fav from that department: Kimi ni Todoke).
I could recommend you many shows but I cannot read your mind and thus will not know what specifically you'd like or wouldn't. I will just post a list of a few shows that seemed good while revisiting the list of anime that I've watched (My MAL profile is
https://myanimelist.net/profile/Vonax if you want to check it out).
Midori no Hibi (already mentioned that)
Mikakunin de Shinkoukei
MM!
Welcome to the N.H.K. (well that one is a bit heavier and doesn't have a school setting but it's one of those anime that you should've watched just because the setting and execution is unique)
Onegai Teacher (and in a similar vein Onegai Twins: they are certainly different but I don't consider them good per se, don't regret having watched them though)
Sakurasou no Pet na Kanojo (pretty good, more comedy-based)
Sankarea (maybe you like the idea of the plot)
School Days (just kidding, don't fucking watch it, you won't like it.. it's certainly..
very unique though and it's good to have watched it. Seriously. It's a bit heavy though)
Sukitte Ii na yo. (Another Shoujo romance just like Kimi ni Todoke, very well made if you want anime with a great focus on romance)
Tonari no Kaibutsu-kun (You'll probably like this)
This list is in alphabetical order so just orientate yourself according to the additions I made in the brackets or simply look them up and see if you might like them.
Hope I could help, feel free to ask for more!