Searching for a yaoi I read a while back.

I don't remember much but I think there was a guy who was always helping people with their relationships but never getting into one himself (though I think he slept around).
And then a guy appears who is interested in him and wants to know how to make him his. (I recall he wasn't much to look at until he decided to change himself to the other guy's liking)
I think there was some kind of reason why the guy who helped work out other people's problems never got into relationships himself but eventually they end up together.

Hope this is enough.

Alright managed to find it myself - Koi no Tsubo