Tristan is already dad to 4-year-old son Prince with Jordan Craig and 3-year-old daughter True with Khloe.
Though Tristan has not publicly acknowledged whether the child is his, the 30-year-old athlete did admit in court documents obtained by the DailyMailto having sex with Maralee in March.
A source tells ET, "Khloe is kind of gloomy about the news of Tristan's new [alleged] baby, especially going into the holidays. Khloe is always so positive, but this brought her down a little. She has always been into giving Tristan tons of chances and deep down held out hope that they would maybe get back together one day. There is no hope and it's really done for now, but she thinks it's for the best."
The source added that though Khloe's outlook on her romantic life might not be the most positive at the moment, "she is so happy to have her baby girl and just wants to move on and be happy."
As for the status of her current relationship with the father of her child, the source tells ET that Khloe and Tristan mostly text, chat and occasionally spend time together, adding, "But it is really only about True."
Though Tristan has always been "supportive" of Khloe, the source tells ET that the Kardashian family is "kind of over him right now."
"They would never trash Tristan in front of True, but they think Khloe needs to put him in his place and not act so nice constantly. He hasn't been great to her," the source adds. "The family is not at all surprised by the news and have Khloe's back and just want her to be fine with it and not sad. They don't think Tristan would ever be faithful and are glad their romantic relationship is done."
And though she's not looking to romantically reconcile with Tristan, Khloe also isn't interested in putting herself out on the dating scene right now, the source says.
"Khloe looks better than ever and her body is on fire, but she is not even trying to date," the source says. "Kim [Kardashian West] says she will set Khloe up and encourages her to go out, but Khloe is not interested in just doing it to get attention or show she has moved on to the media. She is OK being alone right now."
As for Tristan, according to court docs, his alleged third child was conceived in Houston, Texas, during Tristan's 30th birthday celebrations. According toDailyMail, in his deposition, which was made on Aug. 5, Tristan mentions Khloe, who is referred to as his "ex-girlfriend" and the mother of his child.
Khloe and Tristan split in June 2021 amid continued allegations that the athlete had once again been unfaithful to the reality star. One source told ET in September that Tristan still "tries to get her back."
"Khloe gave Tristan several chances and after new allegations decided it was time to break things off," another source said at the time. "The two are on good terms and at the end of the day, Khloe just wants True to have a good relationship with her father."
ET has reached out to Tristan's lawyer for comment about this recent lawsuit.