'The Bachelor' preview: Peter tells Madison he's 'been intimate' with other women

She told him that that would be a sticking point for her.

Peter's confession to Madison on tonight's episode of "The Bachelor" may sink their relationship.

In a sneak peek, the two have a tense conversation in which Madison issues an ultimatum: Stay celibate on the show or she's leaving.

After she explained, "I wouldn't be able to move forward if you have slept with the other women," she added that she didn't want to feel like "a bad person" for having certain expectations.

"You would want to possibly give up a forever with each other because of something that happened this week with another relationship of mine?" Peter asked.

Then he added: "I have been intimate, and I can't lie to you about that."

On last week's episode, Peter ultimately eliminated Kelsey, leaving Madison, Hannah Ann and Victoria F. as the final three. It was also a week for bombshells: An old friend warned Peter that Victoria had destroyed "many relationships," and Madison, addressing the camera, revealed that she has been saving herself for marriage. She has yet to tell Peter.

"The Bachelor" airs tonight at 8 p.m. ET/PT on ABC.