Coworkers girlfriend messaged me from his phone

So I recently posted an ad on kijiji selling a dress, I got a reply and set up a meet up. But as the time before this happens I realize the guys creepy and asked a male coworker to come with me just so I don’t get kidnapped (I work in a mall and it’s just outside my mall the meet up is) so I message him a picture of the time and the guy being creepy in our conversation and I get this reply

Me and this coworker are friends and he had agreed at work and all was good then his girlfriend messaged me through his phone

Below are the ad persons messages just to see why I felt this necessary