One of the bachelorettes who competed on Nick Viall's The Bachelor season reportedly believes she's expecting a child.

Viall "picks a 'good girl' as the winner at the end of the series, but what she doesn't know is that right now one of the other girls he slept with thinks she's pregnant and that it's his," a source told Life & Style, according to OK! Weekly. "Talk about a nightmare!"

The source reportedly claimed Viall was very sexually active while filming his season of The Bachelor.

"Nick definitely sleeps with his three finalists and one other girl, and there are probably at least a few more," said the source.

Viall will enjoy three Fantasy Suite dates later in the season, and viewers have come to presume sleeping with each suitor that's still in the running at that stage is typically a part of The Bachelor process. 

"No one truly knows how many people Nick slept with during his Bachelor run," the source revealed to Life & Style. "But he definitely tried to make moves on every single girl. Some of the women went to first base, some second base and others hit a home run."

ABC has only aired a couple The Bachelor episodes so far, but Viall, a 36-year-old former software salesman from Wisconsin, has already gotten to second base.

On the very first group date of Season 21, bachelorette Corinne Olympios took her bikini top off in the pool during a photo shoot with Viall. He didn't, however, take initiative to grab her breasts -- she asked him to!

The insider explained that alcohol naturally fuels promiscuous behavior on the show.

"When the booze is constantly flowing, protection is not usually on people's minds. And while there are always condoms in the house, with all the drinking going on, there's really no remembering if they were actually used," the source said, attempting to justify how Viall might have gotten a bachelorette pregnant.

Whether Viall's list of sexual partners affects his romance with the woman who received his final rose remains to be seen.

"The winner is already not happy about how much of a pig Nick has been," the source insisted, according to OK! Weekly. "Nick has slept with a good chunk of the contestants but she fell in love with him for other reasons."