Wonderful Life
Cute. An illustrator is in a long term relationship with his high school senpai, but he feels insecure because his senpai is much more financially successful. There's very little drama in this, minus a few minor road bumps in their relationship that are easily resolved. This is something you want to read if you want peaceful fluff.
Honto No Tokoro
Boys competed in high school over everything, but when they reunite randomly as adults the salaryman of the two, Saiki, tells the other one that they don't have to compete anymore. Happy, the other guy, Satou, confesses that he was in love with Saiki entire time and only competed as a way to stay close. Saiki, confused and bewildered, gets swept up by Satou's puppy-seme ways and they end up in a relationship. This couple is pretty cute, wish there were more chapters.
Nichijou Climax
A sweet cute couple of 15 years is suddenly on the rocks when one of them forgets a promise made a long time ago.
Mad Cinderella