Life Senjou no Bokura ????
yeah might be this but they were a couple and same age?
Omg i think i know which one u mean. Let me tryna find it
Nvm i got the it wrong; here is the one i thought it was https://www.mangago.zone/read-manga/wistful_summer/ but reading ur description again its definitely wrong ;‘) sry bout that
Manhwa not manga
Oh its not sadly
Oh i didnt see that
Issok T_T Oh god why is it so hard to find a manhwa
Omg I found it. If anyone wants to know it's Contract Romance for an Ending.
I read it a while ago and I don't remember the plot exactly but it involved 2 friends who meet after years. One of them (the seme) was married to a woman and gets divorced at the beginning and the uke is older than him and iirc a senior of his from high school. The senior had always been in love with the seme but was heartbroken when the latter got married to a woman which left to him avoiding him.
I think the Seme was a teacher (or maybe the Uke was, I can't remember). And I'm very sure the Seme had a black hair and Uke had lighter hair colour.
This is the closest approximation of the premise I could remember. Pls help me find it, ty!!