'I was close friends with my ex. Until his new partner gave him some "rules".'

As told to Ann DeGrey

Divorcing my ex-husband Evan* was one of the best things I've ever done. We'd been together for over a decade, and separating our lives was something we both needed to do because we'd grown apart a long time ago. Somehow, we managed to do it with grace and respect. We had a very close "best friends" relationship, not just for the sake of our two girls, but because we genuinely love and care about each other as friends.

We made a point of staying connected, celebrating birthdays and holidays together, and making sure the kids felt supported by both of us. This was our way of showing the girls that even though their parents were no longer married, they were still a united team.

For three years, everything was going smoothly. I was really proud of how we handled our split and how we were co-parenting. The mums at my kids' school often commented that they'd never guess Evan and I were apart, as we really seemed like a couple, turning up to school events together and seemingly happy together.

Watch: What a healthy co-parenting relationship looks like. Post continues after video.

But everything changed when he got himself an uptight, rude girlfriend, and things went downhill between us. At first, I was genuinely happy for him. He deserved to be happy, and I wanted him to find someone loving and supportive. I'd already re-partnered and was happy, so why wouldn't I want the same for him? When I first met Sally*, I thought she was lovely, but it was all an act and it didn't take long for things to get complicated.

Right away, she started to introduce a bizarre set of new rules. She decided that Evan wasn't allowed to catch up with me aside from the necessary interactions when handing over the kids. This meant our friendly chats, which were mostly about the kids and their schedules, suddenly became a problem.

Initially, I tried to be understanding. I thought maybe Sally was just feeling a bit insecure and that, over time, she'd see that my relationship with Evan was purely platonic. But things went from bad to worse very quickly.

Sally made up a story that I'd said nasty things to her about Evan when she came to collect the girls. She told Evan that I'd told her that he was toxic and she needed to run. This was total rubbish – I never said anything of the sort. I would never bad mouth him, especially not to his new partner. But she insisted, and my ex believed her. It created this awful tension where there didn't need to be any.

"Why did you tell Sally that I'm toxic?" he asked. I was confused and hurt. I tried to explain that I hadn't said anything, but he was loyal to his new girlfriend. He trusted a woman he'd known for three months over a woman he's known for over a decade.

Then Sally decided we should no longer celebrate the kids' birthdays together. This used to be a happy time, where Evan and I would make sure the day was a special one. But now, we have to hold separate parties, which is really sad for the girls as they don't understand why we can't all be together as we used to.

The next rule was that Evan wasn't allowed to come inside my house. This was the worst rule and I couldn't believe he agreed to it. We used to take time to chat and catch up on any updates about the girls' activities, sometimes over a cup of tea. It was something that we both enjoyed and I felt that it helped maintain our co-parenting relationship. Now, he has to wait outside, which just feels awkward.

Listen to This Glorious Mess where we talk about why co-parenting is important. Post continues after audio.

The hardest part is that I have no interest in my ex beyond co-parenting and maintaining the friendship we've built. There's no romantic tension, no hidden agenda. I just want the girls to see that, even though their parents aren't together, we can still be good friends. Now Sally is rocking the boat for no reason. I feel she's threatened by my relationship with Evan and, instead of seeing it for what it is—a mature, friendly co-parenting arrangement—she's turned it into a drama. 

Our girls have noticed the changes. My eight-year-old recently asked why Daddy and I don't talk as much anymore, and that really breaks my heart to see them caught in this tension. I've reassured them that we both love them very much and that sometimes adults need to adjust their relationships. But it's hard for them to understand why things can't go back to the way they were.

It's so frustrating to see our once smooth relationship turned into choppy waters because of someone else's insecurities.

*Names have been changed for privacy.

The author of this story is known to Mamamia but has chosen to remain anonymous for privacy reasons.

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Feature image: Getty.