Recommend me good seinen romance?
I'm talking about things like Hetakoi where people actually get together, have sex, etc. instead of the shounen romance 150 chapters to hold hands
Itoshi no Kana
Koharu no Hibi
Umi no Misaki (had some buildup, but if I recall it had quite a bit of 'action' too)
Sundome and Nana to Kaoru are alright if a perverted relationship is preferred at the start.
Nozoki Ana is that one that seems to be going ok to start, but drags it out a fuck ton similar to Hetakoi.
Futari Ecchi starts under the premise of a newly established couple, but it just kinda devolves from there.
Minamoto-kun Monogatari has many relationships, but where I left off so far he hasn't reached the end and is still in boyfriend bootcamp.
Of course there is haremshit like KissxSis and ToLove Ru Darkness, but I don't think that was what you were looking for?
Whether or not these were what you are looking for, I am not the best judge of quality.
They are just the ones I've read.
I would suggest for continued search to look under tags "seinen" "romance".
Good luck and enjoy (maybe)!