The whole series of mangas with these characters are superior.
We have the first couple here, one being in love for years and the second one giving love a chance and slowly falling in love even deeper. It's such a well-written and drawn manga, THE EXPRESSIONS ARE SO GOOD FUCK, I can literally stare at them for hours. The side characters are great too, the sister and the mutual friend are the MVPs.
Sayonara Game (minaduki Yuu)