Meghan Trainor grew impatient with her boyfriend when he waited months to propose after picking out rings with the pop star.

Actor Daryl Sabara surprised the singer with a big romantic proposal, complete with Christmas lights, members of her family, and music on her 24th birthday in December (17), and he waited so long his bride-to-be didn't see it coming.

Meghan reveals she helped the Spy Kids star select the perfect ring, but he insisted on planning the moment he got down on one knee and asked the All About That Bass singer to be his wife.

"A few months before that we got the ring 'cos I was like, 'I don't wanna get stressed about this; let's both pick it out so we know I love it'," she tells Access Live, adding she just didn't know when Sabara would propose.

"He was like, 'Please let me do a big proposal the right way', and I was like, 'OK, fine'. So he got my parents' permission, everything; he is such a gentleman, it's crazy.

"But that wait was awful. It was just waiting every day, like, 'Is it today? Is it today?'"

Sabara whisked her off to Palm Springs, California for her birthday and Meghan had no idea he was planning to propose.

"It was weird because he was so calm," she adds. "I can tell by looking at him if he's uncomfortable, sad or scared and that day I was like, 'You're so relaxed, it can't be today'... I was wrong."

The loved-up couple have been inseparable ever since mutual pal Chloe Grace Moretz set them up on a blind date after Meghan asked her for a little romance help.

"I went on a tour a week later and I said, 'Do you wanna come visit?' and then he never left, because I didn't let him," she recalls. "Basically, we were just dating and living together and touring the world together right away."

But Trainor insists there's no wedding date locked down, adding, "We haven't even thought about it... We have so much time."