I've mentioned elsewhere that the best erotica preserves the characters' personalities rather than delivering a series of romantic tropes. I'm not opposed to the tropes, but they work better when the characters readers love are not swamped by the tropes.
Summer Days provides Sung Ho and Kwan Haebeom, two very likeable and distinct members of a couple.
They are both big guys, and the writer/artist Jeong Seokchan keeps their proportions, which I always admire in an artist (I am reminded of the earthy and fully fleshed characters of Yugi Yamada). Sung Ho is far more whimsical, even teasing. Kwan is a kind of Rochester: big and gruff and secretly rather sensitive and romantic.
Even better, once the two supposedly heterosexual men realized they are attracted to each other, the relationship moves forward at an even pace. Not a great deal of angst. Despite their differences in personality, they share a common focus on getting stuff done--and becoming lovers is, hey, the next step to getting stuff done!
Delightful storytelling and art.