I’ve been looking for these kind of yaoi mangas for super long but can’t really find much.So what I want basically is
A third wheel that comes into the existing relationship and stirs things up as this third wheel is in love with the seme.The third wheel must be a seme to the seme, so in that case seme becomes an uke but later this third wheel leaves the couple alone and goes away.The third wheel basically has a crush on the seme and wants him.I hope there are some mangas like this. the best example I can give is this webtoon (A Guy Like You)