Please recommend a psychological YAOI that has a happy ending. I want to read something li...

Zenkoku na Kami ga Shihai suru--though it may be difficult to find the ending, it is happy.

http://www.mangago.zone/read-manga/tenshi_no_uta_nishida_higashi/

Its pretty dark but it has a good ending I think.

http://www.mangago.zone/read-manga/cut/
http://www.mangago.zone/read-manga/sono_kuchibiru_ni_yoru_no_tsuyu/
http://www.mangago.zone/read-manga/ienai_itami_o_daite_iru/
http://www.mangago.zone/read-manga/myuzu_no_gakuen_de_aou/ (Only the oneshot "Cage")

http://www.mangago.zone/read-manga/caste_heaven/

This author's mangas are kind of dark and psychological... and very good.

Yoneda Kou's works are awesome in the 'psychological genre'

Try Itou-san manga
http://www.mangago.zone/read-manga/itou_san_kuraka_sui/