As it's a porn game and it seems a huge percentage of players (or maybe just a huge percentage of vocal players) don't seem to handle the fact that a girlfriend may have had a sexual relationship before them, Sage's immediate relationship with Chad has been hinted at as being sexless without overtly stating it.
That way, without saying she did or didn't, the anti-NTR crowd don't feel like they've been cucked by Chad (even if that makes no sense) and the rest of us can assume Chad probably did have sex with her, even if he was gay, because:
- He may not have been 100% certain of his sexuality and he came to terms with it over time,
- He may have had sex with her even if it wasn't his preference (a lot of gay men have married women and had families while denying or hiding their sexuality); or
- He may be bi, in which case Troy being a guy doesn't mean anything, it just means Chad cheated on Sage with someone else.
But what we do know is it's clear he never really was in to Sage, so the question still hangs, why would Sage be head over heels for ~3 years for a guy who is obviously not into her?
I still don't think she cheated on him. When she first gets sexual with the mc she justifies it that Chad started it. Jade does the same thing.