The 20-year-old model and singer are not officially back together but are continuing to talk and see where things go," reported People magazine.
According to the source Kendall remains "hopeful" about her rekindled relationship with Styles, 22, but at the same time is "being more careful".
"He's not going to settle down and she understands that's just the way he is. She really likes him, but her heart's not as invested," the source said.
Last week the former couple went on a dinner date at LA hot spot Ysabel.