It is unclear how long they have been dating, but Derek did pay tribute to Rumer on her birthday.
In August, he gushed on Instagram, “In the short time we’ve been together you have filled my life with joy and peace. Everything is just so easy with you. We sing, we dance, we play and most of all we laugh. Thank you for being you 😘you’re a magical human I’m so glad you came into my life :-).”
Earlier this year, Willis showed some love to Derek, calling him one of the “most talented singers and songwriters I have heard in a very long time.”