Why don't girls believe me when I say I've never been in love?

This may be because most people think that you may be in love. This may be because some of your actions, remarks or appearances have left such an impression on people. In addition, people often misunderstand what they don't know, so they may make judgments based on their own guesses and prejudices.

It is also possible that the girl you met misunderstood what you said. Sometimes, people choose not to believe what others say because of self-protection mechanism, even if there is no evidence to refute it.

However, that doesn't mean you can't change their minds. As long as a good foundation of communication and mutual understanding is established, you can prove your words with practical actions. Time will tell. As long as you treat others sincerely and remain confident, others will eventually see your sincerity.