The insider told Us Weekly magazine: "They were moving too fast.
"They had a fight about how much time they had been spending together but they'll be back. This is a relationship in the fast lane.
"It all moves fast, so the break-ups are dramatic too, like the relationship. They could be back together whenever, it's so dramatic."
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News of the split comes just a few days after the Keeping Up With the Kardashians star declared his love for Blac on Instagram.
Alongside a picture of the green-haired model sleeping on his Instagram account, he wrote: "Love this woman right here so f**k y'all with your negative comments ?? (sic)"
- Bang! Showbiz