Meanwhile, Buchanan, 26, wore a navy blue suit and grey tie, along with a silver watch and yellow sunglasses.
Mouser, 28, posed on the red carpet in a brown, sparkled mini-dress, along with a set of silver necklaces and bracelets.
Buchanan and Mouser’s engagement comes as fans have questioned for years if they were together.
“There's not one person that we don't hang out with and have fun with, and we truly keep saying that we're going to be around in each other's lives forever.
The Independent has contacted representatives for Mouser and Buchanan for comment.
