The 20-year-old 'Give Your Heart A Break' singer - who has dated the former 'That 70s Show' star on and off since 2010 - spent Valentine's Day (14.02.13) with the 33-year-old actor at Takami Sushi & Robata Restaurant in downtown Los Angeles and cuddled throughout their meal.
A source told USMagazine.com: ''They ordered almost everything on the menu, but they didn't touch it for at least an hour. They stared into each other's eyes the whole time.''
The insider revealed the couple only began eating almost an hour after sitting down when they finished a ''really intense conversation'' and were ''cuddling'' throughout their romantic date.
The pair was spotted earlier in the evening ''making out'' at the grand opening of the new Topshop store in L.A.
Demi - who checked into rehab for three months in October 2010 where she successfully received treatment for her eating disorder and problem with self-harming - recently revealed that she is finally in a place where she wants to be in a relationship.
The 'X Factor' USA judge said: ''I'm in a place where I can finally trust and love and be a better person for the man I am in a relationship with, instead of being a clingy girlfriend or getting jealous. It is very unhealthy when girls devote all of their time to a guy and forget their friends and family. I did that. I was always looking for distractions because I was so afraid of being alone.''
Wilmer has always spoken fondly of the 'Skyscraper' singer and previously said he is proud of how she has overcome all the problems in her personal life.
He said: ''We were really just best friends. She's amazing; she's a great human being. And I'm so proud of her considering all of the different obstacles and everything she's been through.''