'Something was "off" about the man I was dating. Then he turned up at my friend’s house.'

I gave a sideways glance at my friend, who wore a similar look of disdain on her face.

"Why don't you rate them?" I said to the drunken guy who'd just invited himself to our table, referring to his opening choice of conversation, which was to ask us to rate his friends in order of attractiveness.

Suddenly, one of those friends appeared and steered him away — back to their own table. He then returned to apologise for his friend's behaviour.

He introduced himself, telling me his name was Mark*. It turned out we were both expats in Australia and had been born in the same hospital.

"Maybe it's fate," he said, with a glint in his eye. He was tall and somewhat handsome — not my usual type, but his confidence was attractive. Besides, dating my type hadn't exactly been working out for me.

Watch: How to tell if you are in a toxic situation. Post continues below.

He asked me to dance, but I declined, saying I wanted to spend the night with my friends. However, when he sought me out again and asked for my number, I gave it to him.

We shared a kiss, and the next day, he messaged me. He mentioned that his mum was visiting Australia, so he would be quite busy for the next couple of weeks, but he wanted to meet again when she left.

A few weeks later, we set a date for Thursday evening. By this point, my memory of what Mark looked like had grown hazy. I knew he was tall and had dark hair, but that was about it.

We'd been communicating through text, so I typed his number into WhatsApp, hoping he had a profile picture. He didn't have WhatsApp, which I thought was a bit strange. I wanted to ask for his Instagram but thought that would be too obvious. All I could do was pray there weren't any other tall, dark-haired guys in the bar where we were meeting.

On the morning of our date, I went spinning. Before getting on my bike, I placed my phone down beside it. During the class, there was an upper-body weights section. As I placed my dumbbells back on the bike, one slipped from my hand and landed directly on my phone.

The screen shattered into smithereens, and I had no way to contact Mark and tell him. We hadn't confirmed a time or a bar yet, so it would look like I was standing him up. I should have taken it as a sign, but instead, I dropped my phone off at a repair shop and picked it up again, shiny and new, on my lunch break.

Who doesn't have social media?

When I texted Mark to explain what happened, I suggested he give me his Instagram, so if there were any further phone disasters, I could log into it on my computer to reach him. "I don't have social media," he wrote back. Alarm bells started ringing in my head.

Who doesn't have social media these days? I thought. But I pushed my concerns aside, reminding myself that it wasn't for everyone. When he explained that he had been on it but wanted a break for mental health reasons, it made a bit more sense.

When the evening arrived, I made my way to meet him.

Thankfully, we arrived around the same time. Although I wasn't initially wowed by his looks, the conversation flowed easily between us. We had drinks for a few hours before going our separate ways — not before sharing a cheeky kiss. We started messaging every day after that and met up several more times before he finally came back to my place, and we slept together.

I hadn't planned it, as I still wasn't sure how I felt about him, but one thing led to another.

He left the next morning, which was a Friday, and I knew I wouldn't see him over the weekend because he was going away with his friends. I was flying back home the following Wednesday for five weeks, and I began to question whether it was worth continuing things with Mark while I was away.

So, while out with my friends on Saturday, I talked it over with them. Since the relationship was relatively new, I hadn't shared much about him, so I filled them in on where he was from, how long he'd been living in Australia, what he did for work, and what he looked like. The more information I shared, the paler one of my friend's faces became.

"What's wrong?" I asked her. "This sounds like my housemate's boyfriend," she replied, leaving me stunned. Surely not? I had no picture to show her, so she went onto her housemate's Instagram profile and pulled up a picture of her boyfriend.

Sure enough, it was Mark, the guy I'd been dating and had just slept with.

'He's not gone away this weekend'.

It turned out that Mark had not only been in a relationship with this girl for nearly two years, but they had also been living together when we first met, as my friend and her were subletting their flat over Christmas. Then came the next bombshell: "He's not gone away this weekend. It's my housemate's birthday, and he's with her. He was at my house last night," my friend told me.

Mark had driven to work from mine without showering and had then gone straight to his girlfriend's house afterwards. It made me feel sick to my stomach.

We decided it was best if my friend told her housemate, but she didn't want to do it on her birthday weekend. Not knowing what I knew, Mark continued to text me, lying about being away and sending me pictures of drinks he was having "with the lads."

I ignored him, knowing exactly who he was drinking with. I couldn't believe he was messaging me while he was with her, especially on her birthday.

My friend finally broke the news to her housemate, and understandably, the girl was heartbroken. When she confronted him, he initially tried to deny it, but I had sent my friend all the messages along with the number he had sent them from, which she confirmed was his.

I haven't heard from Mark since he discovered I knew his secret, but I wouldn't expect a man like that to apologise.

I am now back in the disheartening dating scene, feeling as hopeless as ever about finding a decent man.

I'm beginning to wonder if there are any out there.

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

Feature: Getty.