"Marry Me" singer Jason Derulo can't escape the engagement questions - every interview he sits down to comes with the dreaded question, "When will you and girlfriend Jordin Sparks get engaged?" But now Jason Derulo finally opens up about his planned proposal - but girlfriend Jordin Sparks will have to wait until the "right time."

In an interview with ABC's Nightline, Jason Derulo explains why he wrote the song "Marry Me," and had girlfriend Jordin Sparks star in the music video with him.

"That's the reason why I wrote the song in the first place," Derulo said, "because I wanted her to know that when the time is right then it will happen."

He also made it clear that he was definitely planning on getting engaged to Jordin, and was even thinking about his proposal.

"It will be the most amazing time," the "Wiggle" singer added. "When I do get down on one knee, it's going to be one of the most amazing experiences of my life, but when the time is right."

Jason also gushed about the things that he loves about Jordin Sparks, who he's been dating for 3 years. He especially likes that she reminds him of his mother (creepy?).

"At this point, it's really scary," Derulo said. "My mother doesn't really have a filter. She's really a sweet, sweet woman. She'll tell you how it is... Jordin's the exact same way. She just doesn't have that filter."

He also said Jordin Sparks is "always thinking about others" and is "super charitable."

"She's opened me up to new things," he said.

As we previously reported, Jason Derulo also said that he knew his girlfriend was "the One" when they first started in 2011.

"I knew that pretty early on. I felt that when I was in the hospital with my neck injury," Derulo said. According to E! News, Derulo has previously praised his girlfriend for being instrumental throughout his recovery after he broke his vertebrae in January 2012.

"I felt different...I felt like I needed her in my world."