I read this one a long, long, long time ago, possibly a late 00s/ early 10s manga, most likely oneshot.

I can only remember that somewhere midstory there was a talk between mc and a side character about an ex, by the end of which the mc puts his cigarette in the ashtray saying "I loved him, that idiot" or smth among those lines.

Any help would be much appreciated 🤗🤞