I can't imagine such a situation in real life. Guy has been dating a girl for a year or two, he is not at all interested in her, they don't have sex, their relationship is only for status. I understand that it may be important to emphasize the status of a pair of HOTs-alpha presidents, but in this situation where Chad has no interest in Sage, more realistic scenarios are:
1. They break up after a few months.
2. Sage would start cheating on him. (Sage did, but it was a titter that Chad was cheating on her).
The fact that Sage maintained this unhealthy relationship for so long is like an obsession with Chad, she was madly in love with him. We remember that Sage can be very passionate. But this already crosses all the boundaries of the real life logic.
Although yes, this is a DPCs universe, everything is possible here.
A hot girl with high libido like Sage abstaining from sex, an ex who hasn't had sex in a year in San Diego, a lesbian who suddenly realizes she likes guys. Really, magic world.