The never-ending feud between Kailyn Lowry and Chris Lopez has been well-documented at this point.
The Teen Mom 2 star and her two-time baby daddy continue to never, EVER get along, even as they keep having kids together.
Heck, Lopez is even teaming up with Jenelle Evans these days to tear down Lowry.
But what about Lowry and her very first baby daddy?
Emotions ran high between Kailyn and Jo Rivera on Tuesday night's new episode of Teen Mom 2.
On the latest installment of this MTV franchise, Lowry talked about how son Isaac is almost 10 years old old -- he's mature to have some say in her custody arrangement with his dad.
However, Rivera didn't agree when the topic was awkwardly and angrily broached.
"Why do I have to go to my dad's?" young Isaac asked his mother early on in the episode.
Lowry tried to explain that, "fortunately" for him, he has a dad who wants to have custody of him half of the time.
"You're actually so lucky," she explained because for some kids, "one of the parents' isn't always there.
"You're very lucky your dad wants to be there and spend the time with you."
But Isaac is 9, you know?
"I do the same thing every day and I can't do anything else because he doesn't plan anything special," the child said, adding of Rivera:
"He's always at work and stuff."
Lowry continued to talk up her ex, telling Isaac she'll have a "great week" with his father. She responded in very fair fashion.
When she got together late on with friends, though? Kailyn delved into the discomfort of the situation.
"I don't think Isaac tells Jo. I think he's very aware of other people's feelings. He's not going to tell his dad how he feels because he doesn't want to hurt his feelings," she said.
Alhough she said she doesn't "want my kid to be miserable," she also didn't want Jo to "feel attacked" if she got into all this with him.
Eventually, however, Kailyn and Jo did discuss it... off camera.
"I told Jo I felt like Isaac was old enough to choose if he wanted to stay a couple extra days with him or a couple extra days with me and he said no," she told her pals after the call.
"He said he doesn't believe Isaac is old enough to make those decisions," she continued.
"He's about to be 10, he should be able to decide if he wants to stay over there for an extra day or two. Isaac's getting older, his needs and wants are changing.
"And with that comes a shift in coparenting and a shift in what we think is best for him."
Lowry made it clear, despite her above stance, that Jo is a solid dad and she doesn't plan on taking him to court to battle for more custody of Isaac.
She was adament when it came to this second point, and very fair overall when assessing the dilemma.
"We're just gonna have different opinions and we're gonna have to work through it," she said.
"I think this is the start of a lot of differences to come."
Despite quite a few differences over the years, Lowry and Rivera are currently in a good place.
"I definitely think Jo and I hit a breakthrough this season, which I'm pretty proud of," Lowry told TooFab ahead of the Teen Mom 2 premiere. "I think that there's always been an underlying resentment, even during the good times with Jo."
She also said that a revelation with her therapist played a huge role in the dynamic change between the exes.
"It's hard to face the music sometimes and when you know you're wrong or you finally look in the mirror and like, 'Wow, I could have made a better choice or I'm going to do better moving forward,'" Lowry continued, impressively self-aware.
"But I hope that the viewers get that from this particular breakthrough that I’m referring to so.
"Jo and I, we're in a good place now and I hope it stays that way."