Bookout, who has a 3-year-old son called Bentley, split from King in January but is now thought to have re-evaluated the relationship after watching Teen Mom.
"It made her realise how crazy she'd been acting," a source told Us Weekly.
The insider also claimed that the duo "hook up", adding that they have been "inseparable" lately.
Meanwhile, Bookout admitted: "I'd be lying if I said I didn't think [Kyle was The One]... There's obviously a reason he's still around... [but] I've taken a step back and realised I'm only 20. There's no need to rush into anything."
Bookout also suggested that she could have a relationship with King now, but said: "We'd rather figure ourselves out first and then try to make a life together."
The 20-year-old is currently appearing in her final season of Teen Mom, which airs Tuesdays at 10/9c.