Law enforcement sources tell TMZ ... a fan showed up to Trisha's pad in Los Angeles and tried to profess his love for her. We're told he bounced when cops were called, but not before leaving his name and number with her friend.

Our sources say when the guy first arrived unannounced, he started going up the driveway towards the front door when he was stopped by Trisha's male friend.

We're told Trisha was inside the home while her friend went outside to see what was up, and the trespasser said he was there to confess his love for Paytas.

Our sources say Trisha's friend told the guy to beat it, but he initially refused and that's when cops were called.

We're told police took a trespassing report and the case will be sent to the L.A. City Attorney.

Should be a pretty easy arrest if the City Attorney wants to press charges.

Stay in school kids.