Star x Fanboy
tamen de gushi
Voice of love
Voice of love as well is good
Though the 3 main characters aren't involved romantically, you will find many uwu gay couples in the later chapters plus the the author of 19 days is involved in making it too
http://www.mangago.me/read-manga/mosspaca_advertising_department/
They aren't really like 19 days or Bromance webcomic (which are clearly of shounen ai genre) but these 3 mangas will make you ship the lead male characters sooooooooo much
http://www.mangago.me/read-manga/koimonogatari/
http://www.mangago.me/read-manga/hinatama/
http://www.mangago.me/read-manga/adekan/
Anything like 19 days or Bromance ?