Not something tragic, but something deep that makes you sigh at how beautiful their love for each other is (not just smut)
try checking this list if you hasn't read it yet (=・ω・=)
http://www.mangago.me/home/mangalist/12765/
http://www.mangago.me/home/mangalist/25771/
give these a go :)
http://www.mangago.me/read-manga/koimonogatari/
http://www.mangago.me/read-manga/hidamari_ga_kikoeru/
http://www.mangago.me/read-manga/haikei_niisan_sama/
http://www.mangago.me/read-manga/hana_wa_saku_ka/
http://www.mangago.me/read-manga/yuuutsu_na_asa/
http://www.mangago.me/read-manga/itoshi_no_nekokke/
http://www.mangago.me/read-manga/blue_sky_complex/
http://www.mangago.me/read-manga/hana_no_mizo_shiru/
http://www.mangago.me/read-manga/sayonara_itoshi_no_my_friend/
http://www.mangago.me/read-manga/slow_starter_ichikawa_kei/
http://www.mangago.me/read-manga/500_nen_no_itonami/
http://www.mangago.me/read-manga/hana_no_miyako_de/
Any good mangas with a MC who's a strategic/analytical thinker, and that's what sets him/her apart? It can be any genre (shonen, shojo,...)
Death Note, Code Geass, Oldman, No. 6, Ludwig Kakumei (a very underrated manga), Itou-san, Haru no Houtai Shoujo, Ayeshah's Secret, All You Need Is Kill, SnK, Kanshikan Tsunemori Akane.