I dunno about particular tropes, but as for works as a whole...
Most yaoi is just gratuitous smut and/or fluff. Fun to read, but fairly problematic and it often fetishizes gay sex. Which is fine as long as the reader understands that it’s an unrealistic fantasy usually by females for females. There is absolutely nothing wrong with all that, it just makes for a genre full of cliches.
The only yaoi I can think of that I would call a classic is Life Senjou no Boukra. (Spoiler alert run far and fast if you don’t want to be spoiled) Even if the characters grow old and pass, the message of the work will never grow old.
Sorry this got kind of long, but I really loved your question. Tbh I’ve got more to say so hit me up if you want me to write a dissertation on this lol.
To me the difference is that cliches lack originality, and they're boring. A classic to me, is something that is or was, original, however is now being used often. When it comes to yaoi of course. It's kinda hard to explain..
Just occurred to me that I never answered the question directly. I think a classic is something that conveys a timeless message and will always be relevant while cliches can be fun to read but little more than that.
Hahaha I know what they mean that's why I asked what would be considered classic in yaoi since it's full of clichés.I love the manga you gave as an example,it made me cry...
Everything was once original but I think I understand what you mean
when it loses it meaning and gets repetitive, its a cliche. if you can 'never' recreate it, i'd consider it a classic.
What do you think it's the difference between cliché and classic in yaoi?I can think of a ton clichés but 0 classics,even the childhood friend thing is executed poorly most of the time to become a classic...