In season six, episode six, of MTV's "Teen Mom 2," Chelsea Houska loses her ally in a custody battle with ex-boyfriend Adam Lind, Jenelle Evans starts to question her relationship with Nathan Griffith, Kailyn Lowry finally makes peace with husband Javi Marroquin and Leah Messer's marriage with Jeremy Calvert falls apart.

Evans' mother Barbara finally gives in and lets Evans spend time with her son Jace. But as the custody battle with her mother reaches a peaceful arc, it's her relationship with fiancé Nathan Griffith that starts to boil over. The couple has been fighting since they returned from their engagement trip in St. Thomas. The tension reaches its peak when Griffith gets verbally abusive towards Evans before skipping town on an unannounced business trip.

"You're trailer trash who hit the lottery, you're nothing special," Griffith tells Evans during a heated argument. "You're a f---ing waste of life, dude."

Houska joins forces with Taylor Halbur, the fellow ex-girlfriend of Lind who is also the father of the girls' respective daughters. Halbur and Houska hire the same lawyer to fight Lind's request for 50/50 custody of daughters Aubree and Paislee, but Houska isn't happy when she finds out that Halbur decides to settle with Lind out of court.

"That's not good because we're supposed to be working together against Adam," Houska says to a friend. "I don't care what people do, but if that's gonna mess up my court case, I'm not gonna be happy."

In an attempt to fix the problems in their rocky marriage, Marroquin books a night in Philadelphia with Lowry so the couple can enjoy some time together without the kids. They barely make it to the city before another argument breaks out in the car, this time over Lowry's friend Sterling who wants to join them on their upcoming family trip to Florida. Distracted by their argument, Marroquin doesn't see a piece of wood in the middle of the road and runs right over it, causing a flat tire. After a heart-to-heart with his sister, he realizes he needs to be more accepting of Lowry's friends and her social life.

"I really do wanna change," Marroquin tells Lowry. "If your friends are taking time out of their lives to be with you and be with all of us so we can have a good time, I'm appreciative of that."

Messer's marriage with Calvert hits a point of no return when the couple argues over the phone about finances. Calvert then confides to a friend that finances are the least of the couple's worries. He makes his mind up, and wants to file for divorce. Calvert moves in with his parents, and the two meet up when Messer drops their daughter off to spend the weekend with him. The couple gets into another argument when Calvert starts listing off the reasons why he wants a divorce, and Messer drives off, crying and talking to herself.

"There's nothing like going through issues alone for three years," she says to herself, crying. "He doesn't know, he was never there."

Watch a clip from the episode below.