Well, we can do it in Dragon Age II ; why not Mass Effect 3 ?
Although it actually raised the ire of a few heterosexual gamers who thought the option for gay relationships was a bit too in-their-face, BioWare's DAII allowed same-sex fun between a leading male protagonist and other male characters. Now, Mass Effect executive producer Casey Hudson has confirmed via Twitter that ME3 will also boast "wider options for love interests:"
"Happy to confirm #ME3 supports wider options for love interests incl. same-sex for m&f chars, reactive to how you interact w/them in-game."
So yeah, if you like, protagonist Shepard will be able to show affection to other men. In past installments in the series, players could get characters to engage in male/female, lesbian and alien (Asari) sex, but some in the gay community noted the complete lack of a possible gay coupling for the main character. But after DAII, we figured BioWare would make the change for ME3.