Demi Lovato and Guilherme ?Bomba? Vasconcelos have ended their relationship after dating on and off since July 2016. The pair started hooking up in the summer of last year just after Lovato and Wilmer Valderrama ended their six-year relationship. A source told Us Weekly that she and the MMA fighter were ?just having fun? at the time and that she was ?still looking to meet new guys.? ?Bomba is a good guy, but the relationship just ran its course,? they added.