http://www.mangago.zone/read-manga/ashita_shinu/
Personally, some might be tearjerkers, but these are pretty mild.
I may not be the best person to answer your question as twisted & tragic BL is my forte, but I think these 2 stories might just be in your tolerance range -
http://www.mangago.zone/read-manga/triangle_fuuki_mame/
http://www.mangago.zone/read-manga/yuki_iro_machiboke/
They are tragic but also VERY SWEET with happy ending.
http://www.mangago.zone/read-manga/hana_to_ryuu/
Definitely not a happy ending but so good you just can't stop yourself...
http://www.mangago.zone/read-manga/hana_no_miyako_de/ This one is listed as tragedy, but I find it more heartbreaking than tragic. Really great read though. Enjoy!
Some of them have happy endings some not, some of them are very fcking sad and some not but here u go (=・ω・=)
http://www.mangago.zone/read-manga/lonely_to_organdy/
http://www.mangago.zone/read-manga/cut/
http://www.mangago.zone/read-manga/boys_love/
http://www.mangago.zone/read-manga/ze/
http://www.mangago.zone/read-manga/no_6/
http://www.mangago.zone/read-manga/1999_shanghai/
http://www.mangago.zone/read-manga/pieta/
http://www.mangago.zone/read-manga/life_senjou_no_bokura/
http://www.mangago.zone/read-manga/pure_dakkang/
I vehemently avoid all kinds of tragedy but I kind of want to dip my toes into the genre now. Is there any tragedy Yuri or yaoi that you'd recommend that isn't too... Tragic??