Belly and Jeremiah break up primarily because Jeremiah cheated on her during their spring break. Jeremiah had a physical encounter with a sorority member named Lacie Barone at a fraternity party in Cabo. This happened while they were supposedly "on a break" after a fight right before spring break, but Belly did not see their relationship as broken up at that time, viewing it as a misunderstanding. When Belly overheard someone talking about the incident, she confronted Jeremiah, who admitted what happened but maintained that since they were "on a break," it wasn't cheating. Feeling betrayed and devastated, Belly slapped Jeremiah and ended the relationship. Though they briefly get back together and Jeremiah proposes to Belly, the trust damage remains. Ultimately, the relationship does not last, as unresolved feelings and complications lead them to cancel their wedding and break up for good. Jeremiah acknowledges that Conrad (Belly’s other love interest) is her true soulmate, which further cements their final breakup. In summary, their breakup is deeply tied to Jeremiah's cheating incident during a break in their relationship, Belly's resulting heartbreak, and the complex love triangle involving Conrad.
