You want to know something I’ve realized rather recently? Please, correct me if I’m wrong, but to my knowledge, the very first time Jason speaks to Kelsi on-screen is when he’s raising his voice to reprimand her for signing him up to do the school musical in High School Musical 3: Senior Year. This means that they had an entire relationship throughout High School Musical 2 and between the events of HSM2 and 3, without ever saying a single word to each other on-screen. I can’t tell if that’s impressive or pathetic.
Regardless, Jason and Kelsi’s relationship was just one more casualty of the terrible writing that plagues HSM3. Sure, we don’t really know what the relationship between these two was like, thanks to the very minimal insight we’re given to their dynamic. And, Jason steadily becomes more of a douchebag as the series progresses, which implies that he might have, in fact, been a bad boyfriend. But, the fact remains that Peter Barsocchini and Kenny Ortega abruptly broke them up for no given reason to suddenly have Kelsi become Ryan’s unnecessary beard.
In one of the deleted scenes, it’s revealed that Jason asked Martha to the prom. In a supplementary book for HSM3, you see how he went about doing this, and in the film itself, Jason wears this shirt:
It’s hard to tell, since someone tried to cover it up, but the blue text reads, ”Jason + Martha = PROM”. Evidently, there was an intention to build a relationship between Jason and Martha. It’s even possible that Jason might have dumped Kelsi to make himself available for Martha, which further paints him in an unflattering light, since dumping an introverted drama geek for the head cheerleader is a douchey move. But this Jason/Martha relationship is almost non-existent in the final product, with only a few, barely noticeable instances of them interacting to hint at a relationship at all.
This is due, no doubt, to the nauseating level of focus on Troy and Gabriella’s relationship that utterly saturates this movie at the expense of other characters and their stories.
All that said, I still think that Jason and Kelsi were adorable together in what little glimpses of their relationship we saw, like this one-
-and I wish that the writers wouldn’t have split them up just to attempt to shove Ryan back into the closet.
Thank you for asking! :)