The gorgeous 26-year-old personality joined the "The Ellen DeGeneres Show" this week to discuss her year-long relationship with the Lakers hooper ... admitting their relationship could've started a LOT sooner if it weren't for a social media hiccup.

"I got a DM a year prior from my boyfriend, and I never seen it," Harlow told guest host tWitch. "I don't know what the glitch in the system with Instagram is, but that never came up for me!"

But, Kuz wasn't about to give up on his dream girl that easily ... so he tried one more time to get Winnie to respond.

"A year later, at the top of quarantine, he DMed me again. He posted a picture of me in an outfit and I was like, 'Oh, hi!' ... and he shot his shot. He slid into the DMs."

"That was cute, and I was like, 'Oh hey, how's quarantine been?'"

Harlow says the DMs turned into FaceTimes every day ... which turned into Kuz asking her to quarantine with him in L.A. Of course, she said yes!!

Remember, TMZ Sports posted photos of the couple out in L.A. back in May 2020 ... holding hands and taking their quarantine love public for the first time.

Fast-forward to today, and it's clear they're as strong as ever!!