Based off of this song http://www.youtube.com/watch?v=PZjn5rmKHws

[The main lyrics that grabbed my attention, In english of course]
Rose: I don't care whose you are
I will love you
Diego: I won't hand you over to anyone

Despite how it seems Tech is not gay. He has no orientation and will fall for anyone regardless of race, gender, whatever, the reason he is more comfortable with guys is because he was always around them and he did fall for Diego at a young age (Around 11 he really started noticing, but was with him way more than Max sense they met when he was 9)

Diego was Tech's first crush but do to some manipulation Diego left, knocking Tech out in the process to stop him from following him, something that almost shattered his already weak memory (and the reason Tech and Diego have the same hair and clothing style)

Rose is the princess of the Plains that Tech met and protected when he turned 20. He treated her very kindly and did not give her special attention because of her status or even because she was a girl, he treated her exactly like everyone else. She developed a crush almost instantly and Tech's oblivious nature made it worse sense he kept leading her on without noticing.

The problems start when due to circumstances Diego comes back and accidentally breaks part of Tech's seal, the dual personality of Tech and Rai making the love triangle alot more complicated, especally when Rai assured Diego they (Both him and Tech) still loved him and Rose who promised to be around no matter what.