As told to Ann DeGrey.

For six years, Liam* was my world, my everything.

I really loved him so much. We met through friends and fell madly in love. I thought we'd end up getting married, having kids, all the clichés.

I thought things were fine when one day he said he wanted to talk to me about something that was very important. I thought maybe it was about buying a house or moving interstate, things we'd discussed before.

Instead, he told me he wanted an open relationship.

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At first, he was quite casual about it, saying he had a few friends who had tried it out.

"Lots of couples do it now," he said. "Just to keep things fresh."

I said no right away, but he kept bringing it up. Week after week, he was really getting obsessed with the idea. He'd read articles, seen some YouTube videos and got me to watch some examples of happy poly couples on social media. I hated the idea. The thought of him with someone else made feel ill.

I told him no, over and over. I explained that trust was already our foundation; why risk ruining that? He seemed very disappointed, and it wasn't until he admitted that he wasn't happy and felt trapped that I realised he was very serious.

He made it clear that if I didn't agree to an open relationship, he'd start having affairs.

So the pressure built slowly. He stopped being affectionate. After a year of this, I was exhausted. I loved him more than anything, and I was terrified of losing him.

So, one night, I finally agreed to give it a go.

He was thrilled, but I said we had to agree on rules; we had to tell each other everything and no falling in love with others.

I downloaded a couple of dating apps the same week he did. I kept my profile simple and had a few matches. Most conversations died after a few messages. I went on just two coffee dates. Both times I left early, feeling weird about it all.

I didn't think it was exciting at all as my heart just wasn't into it. I kept thinking about Liam.

For him, it was different. Within weeks, he had three women he was seeing regularly. He came home absolutely glowing, full of stories about the women he was dating.

This was very difficult for me to hear.

He'd go out for "drinks" that lasted until midnight. I tried to be supportive. I smiled when he told me about Anna, the yoga instructor, or Mel from his office.

But inside I felt smaller every day. My self-esteem took a huge hit.

A few months later, the cracks started to appear. Liam grew distant, and we hardly spent any time together. He said he was "busy exploring," but it wasn't long before he told me he'd fallen in love with one of his girlfriends. She told him she wanted him all to herself and insisted he break up with me.

He was gone the next day, as he moved into her apartment. He returned a few times to collect his things, while I sat sobbing on the couch. The worst part wasn't even the leaving. It was learning that their relationship was not an open one. It was just the two of them, building something traditional.

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Now I think he was such an arsehole, that he'd pressured me for years to try an open relationship. Then the moment it worked for him, he slammed the door shut on me.

I kept thinking about all the nights I'd forced myself to be okay with his dates while I got nothing in return. I'd tried to date other men, but I just wanted to be with Liam, and he knew that.

But the dating world never worked for me the way it did for him. All my friends say I was brave for trying and for making him happy. But mostly I just feel like an idiot.

He was probably planning on leaving me the whole time. I believe he just used the open relationship idea as an excuse. If I could go back, I'd keep saying no and mean it. Because an open relationship didn't set us free. It just showed me how one-sided our love had become.

I'm 39 now and I've had to re-start my life with a broken heart. I wish I'd just trusted my gut, because if something feels wrong from the start, it probably is.

*Names have been changed to protect identities.

Feature Image: Getty. (Stock image for illustrative purposes).