Welll... i can only think of the belove ones ..they are not exact maches tought
http://www.mangago.me/read-manga/crush_on_you/
the girls are not mc tought, but they are important
http://www.mangago.me/read-manga/koi_ga_bokura_wo_yurusu_hani/
http://www.mangago.me/read-manga/sojou_no_koi_wa_nido_haneru/
Here the mc is hermaphrodite and has to choose a girl or a boy to be with and to decide his/her sex..... the girl loves him/her very much and he /she loves both the girl and the boy and they kind of competee for the mc .... dont know if it qualyfies
http://www.mangago.me/read-manga/after_school_nightmare/
Let me know if you like them
Hmm...I only know of this one - http://www.mangago.me/read-manga/kare_no_aijou_no_hakari/
There's also a similar situation here - http://www.mangago.me/read-manga/cherish/ (But, it's just the back story. Not the main one)
I want to read a manga where the story involves a girl who likes a gay guy or falls in love with one. thanks