The 23-year-old singer discussed the 36-year-old actor in the June/July issue of Latina magazine, claiming Valderrama is more emotive than any of the white men she previously dated.
"When I dated white guys, it wasn't as passionate as my relationship with Wilmer," Lovato declared. "Maybe that's just Wilmer. But I do believe that Latin people are just more expressive, more passionate with their emotions."
"He's very manly, and he can be stubborn like Latino men can, but he's protective and he cares so much and loves so hard," she added. "I've been blessed enough to have him in my life, and not just as my man, but also my best friend."
Lovato is of Mexican, Irish and English heritage, while Valderrama is of Columbian and Venezuelan descent. The couple celebrated their six-year anniversary in January and often share photos together on social media.
"I met him five years ago and we became close after that," the singer revealed on On Air with Ryan Seacrest in September. "I looked at him and was like, extremely attracted to him. Who isn't?"
Lovato and Valderrama have weathered a number of personal issues, including the singer's eating disorder and substance abuse. Lovato celebrated her fourth year of sobriety in March and credited Valderrama with helping her through her struggle with bulimia.
"I've been my heaviest in my relationship with Wilmer and also been my thinnest," she told Latina. "He's seen it all and loves me equally, and it gives me confidence to know that."
Lovato last released Confident in October and will kick off her Future Now tour with Nick Jonas on June 24. Valderrama, meanwhile, recently guest starred on ABC medical drama Grey's Anatomy.