That would not be sinful.Nobody's expecting or condoning you to have an affair or some such Hoping.
Newsflash, there are such things as monogamous homosexual couples...
Just as two thieves or liars living together wouldn't be sinful.
It is the lies, the thefts, and any other unholy things that God despises.
If one doesn't give in to temptation, there can be so sin.