Chuck has similar problems, and he's anti-almost-everything too (including his poor students), so if you can put up with him, it shouldn't be too much of a stretch to put up with "Stephen" =)

As for Chuck cheating on Geoffrey - he does that in canon. Without using protection, even. (See "Jerri's Burning Issue".) Not to mention that the whole relationship with Geoffrey is itself cheating on Clair. ("Who?" "Your wife.")

...so, basically, if you like faithful and healthy relationships, you're fangirling the wrong show =P