"A man who was already in a relationship sent me an inappropriate message, so I told his girlfriend."

Very recently, I made an executive decision: if a man who is already in a relationship hits on me, I’m telling their partner.

It wasn’t a choice that came out of the blue, it was a place I came to after numerous men who were already taken decided to hit on me. Some of these men were aware of that fact I’m currently in a relationship myself and clearly unavailable. Yet they had still decided that it was okay to send me inappropriate messages at inappropriate times.

On one occasion, a man decided to straight up kiss me. I’d had enough. 

When men like this have overstepped that boundary in the past, before even feeling personally violated, I’ve had one other over riding reaction. I’ve felt awful for my partner and also theirs. But on the last instance of this behaviour, something changed. This time, I got angry. ‘How dare they try to involve me in their selfish behaviour, which upsets numerous unwilling victims?’ I thought to myself.

It was an event that happened last Saturday night that presented the straw that broke the camel’s back, and potentially someone's relationship. After a wild night of watching movies with my boyfriend, I woke up in the morning to a late night message from a man. I had to try and work out the hell he was, and who the hell he thought he was. Looking at our past messages, I worked out that he was a random guy who tried to add me after seeing me on Tinder – two years ago in my single days.

I went on his Facebook profile and discovered two things: that he supports Trump and he had what looked like a girlfriend in his pictures. His relationship status was confirmed when I went on his girlfriend's Facebook page. She was stunning but that's beside the point. I thought she deserved to know, so I messaged her.

In my message, I told her that I felt her boyfriend's actions were inappropriate, and if my boyfriend had been sending late-night messages to other, random girls, I would want to know. I awaited her reply, hoping she would tell me I was a presumptuous idiot, and that they were just friends.

In her reply, she was graceful and lovely which made me feel even worse that her boyfriend had disrespected her. Like any smart woman, she asked for screenshots, and I obliged. She told me that she appreciated me telling her of boyfriend's transgression. The pair probably are still together, and have moved past the incident. But I still don't regret telling her.

I've watched too many friends stay in relationships where they suspected their partner was cheating but didn't have the firsthand evidence they needed to confront them about it. They more often than not found out that their partners were after the relationship had ended.

I've also had friends who were told that their partner had cheated on them, and decided to stay in the relationship. Their friendships however, were damaged in the short term. Yet when the inevitable break up happened with their partner, they appreciated the honesty of their friends and their subsequent friendships became stronger than ever.

Telling on a cheating or inappropriate partner isn't an easy decision – but it's the right one. You may be the messenger that gets shot, but you could also be the person who gives someone what they need to walk away from a toxic relationship. You need to prepare yourself for any outcome, and accept that how this impacts their relationship is not up to you.

I'm glad I told this woman about her partner's inappropriate behaviour and if I have to do it again, I know I will.