The most understandable possible explanation that we've heard so far is that their schedules just got too busy and it was hard for them to find time together. According to TMZ, the pair was fighting over which events to attend together - and when they did, it meant one or the other scrapping their plans.
Now, another theory has surfaced, claiming that Kylie and Tyga actually broke up over Kylie's rumored former boyfriend Jaden Smith.
"Kylie and Jaden have been hanging out lately and it made Tyga suspicious. He thought something might be going on. So that was one issue," a source told E! News.
Another source, however, tells them that's not the case. "She has a close relationship with Jaden since they were very young but nothing romantic has happened with them since she has been with Tyga. Jaden though will always love Kylie and Kylie will always have a love for Jaden. They grew up together and were each others' first loves," their second source explained.
A third theory claims that it was "something Tyga did," although the source that revealed that to TMZ wouldn't elaborate.
To the former couple's credit, they have remained tight-lipped about the whole thing and aren't airing any of their dirty laundry out in public.