Why would a guy lose interest if I tell him I hooked up with someone else if we aren’t dating?

Anonymous

I asked if I was the last person I hooked up with and he said yes and then I told him he wasn’t the last guy I hooked up with and he was like it’s what ever we aren’t dating then after that he stopped calling me cute nicknames and made excuses of why he didn’t want to see me anymore and it made me upset. Why would he lose interest because of this and was it my mistake by me telling him this? Now he’s not calling me sweet names anymore and is not interested in me anymore. Was it my mistake by telling him this? Now he thinks way different of me now when I’m really a sweet girl that deserves a chance. I didn’t do anything wrong.
Why would a guy lose interest if I tell him I hooked up with someone else if we aren’t dating?
5 Opinion