Any Suggestions? Gore or Obsessive Love?

For gore and horror try Gantz (shudder ... tried the anime and could not get too far) Shingeki no Kyojin, Tokyo Ghoul

hi there~ i LOVE obsessive love and dark mangas too. its like a dark treat haha

BL Obsessive Love

http://www.mangago.zone/read-manga/sakura_gari/ (obsessive-longing love)

http://www.mangago.zone/read-manga/killing_stalking/
(psychotic in general, with love stuff also)

(many other BL have light obsessive love to a certain extent but since you said psychotic I'll only recommend these because im guessing you want more dark stuff)
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Obsessive Love Shoujo (all of them shoujo/aimed to girls)

http://www.mangago.zone/read-manga/flowers_of_evil/ (warning incest. but very hardcore obsessive love)

http://www.mangago.zone/read-manga/aishite_kudasai_sensei/ (obsessive love for sensei)

http://www.mangago.zone/read-manga/bokura_no_koi_wa_shi_ni_itaru_yamai_no_you_de/ (obsessive love for girl who used to love his brother)

http://www.mangago.zone/read-manga/watashi_no_megane_kun/ (both girl and guy have obsessive love for eachother.. my least favorite out of the list but still a good read for obsessive love)

Wahh!! Fufufu~!! Domo arigatogusaimasu desu!!! ^~^ hehehe.. (Killing stalking is one of the best manga that i've ever read.. •~• again, thanxaaa!!

heh~~~ you're welcome my friend ^__^!!!!