Poor Kylie Jenner. The 20-year-old reality star has been mostly in hiding since it was first reported she’s pregnant. And it turns out her reclusive lifestyle has caused some problems in her personal life — as In Touch has learned that Travis Scott, the father of her unborn baby, has been cheating on her.

“Travis is cheating on Kylie with a hot 20-year-old he met while making a music video. It’s beeing going on for a while. Travis says he loves her,” a source tells In Touch exclusively. According to the source, Kylie is blissfully unaware of the affair. “Kylie would die if she found out. Travis is in love, but not with Kylie.”

Our source says that Travis first met his mystery woman towards the end of last year on a music video set. The two allegedly exchanged numbers, and stayed in touch — and they eventually rekindled their romance over the summer (at that point, Kylie was already pregnant with his child).

“He was definitely acting like he was single,” the source says of a summer party thrown by Travis, and attended by his mystery woman. “That was the first time Travis and the woman hooked up.” According to the source, he worn protection while sleeping with the unnamed mistress. The source adds, “He learned his lesson.”

Even though Travis is secretly seeing another woman, he has had no problem wooing Kylie, and playing the role of doting boyfriend and father-to-be. “Travis and Kylie have been talking marriage,” an insider tells In Touch exclusively. “Kylie’s crazy about Travis, and now that she’s pregnant she is pushing him to take their relationship to the next level.”

But the original source says the makeup mogul shouldn’t be so optimistic. “He can’t be that serious with Kylie,” the source explains. “He’s hooking up with another girl! It’s really sad because Kylie obviously wants to make this relationship work.”

Have a tip? Send it to us! Email In Touch at contact@intouchweekly.com.