
Im confused.. like why she waited so long for the backstory? I literally forgot he even had one the whole time.

I think you are new to her work or into BLs I'll try to be simple with explaining then, see author didn't drag it it's called "plot pattern" a strategy to put which situation and when things should be unveiled is the popularity factor of story(you can't just put anything anywhere) a proper script, dialogues, rough drafts are made before making the bls or any comic with character design sheet and refrence material.
In first season author introduced readers with her main characters (Dan) and his background story , further elaborated about character's life , struggle and the thier life style author later established Dan's relation with other side character and main character (jaekyung) all the physical and emotional tension between jaekyung and Dan worked as build up that left an impression on readers, Dan's leaving jaekyung worked as an raise in intrest among readers for S2 ( see this is all a strategy to make plot intresting) by the end of S2 readers accumulated enough hate for jaekyung ( which played important role in jaekyung popularity that author wanted) example: stretch the rubber as tight to increase it's impact once released " author used the hate to for impact, his injury was a part of the strategy.
Where S1 plot was from Dan's viewpoint With start of S2 the viewpoint changed from Dan to jaekyung now the story started from jaekyung's viewpoint his injury kept him away from ring which gave him enough time to reflect, he chase Dan to manipulate him to get back for his own benefit but as he realise Dan's circumstances jaekyung starts to develop feelings for Dan in the process ( that's love right there ) now the plot don't get boring with chasing

I think you are new to her work or into BLs I'll try to be simple with explaining then, see author didn't drag it it's called "plot pattern" a strategy to put which situation and when things should be unveiled is the popularity factor of story(you can't just put anything anywhere) a proper script, dialogues, rough drafts are made before making the bls or any comic with character design sheet and refrence material.
In first season author introduced readers with her main characters (Dan) and his background story , further elaborated about character's life , struggle and the thier life style author later established Dan's relation with other side character and main character (jaekyung) all the physical and emotional tension between jaekyung and Dan worked as build up that left an impression on readers, Dan's leaving jaekyung worked as an raise in intrest among readers for S2 ( see this is all a strategy to make plot intresting) by the end of S2 readers accumulated enough hate for jaekyung ( which played important role in jaekyung popularity that author wanted) example: stretch the rubber as tight to increase it's impact once released " author used the hate to for impact, his injury was a part of the strategy.
Where S1 plot was from Dan's viewpoint With start of S2 the viewpoint changed from Dan to jaekyung now the story started from jaekyung's viewpoint his injury kept him away from ring which gave him enough time to reflect, he chase Dan to manipulate him to get back for his own benefit but as he realise Dan's circumstances jaekyung starts to develop feelings for Dan in the process ( that's love right there ) now the plot don't get boring with just chasing and reluctance it was the time to release the rubber, the accumulated hate everyone had for jaekyung to clear it with his background story and leave a fresh impression of him on everyone.
My prediction : and now the beach incident has left jaekyung terrified he he has realised that Dan matters in his life now maybe soon we will see jaekyung chase for Dan with love. And that blond MMA relation with jaekyung is yet to be unfold
I hope it helps you to understand it better

I know but doesnt she think it should’ve been a lot more earlier? I mean cause like multiple people already drop this and I feel like it’s too late to give him a sad backstory especially when she missed a lot of opportunity in this that would’ve made sense if he had his backstory right there. Idk my opinion but Ty for telling me why this have been on a hiatus for quite a long time.

Nah bro that's not the reason , you see the plot of any manhwa manga or manhua is written and planned out before the it's publication stage in short the author already know the ending. Her surgery was unexpected (health issues can't be predicted) and the fact she actually kept posting her surgery due to the manhwa.
Sorry i can not read this his face pmo