Selena Gomez almost missed Benny Blanco's proposal because she was "grumpy"

Speaking on 'The Tonight Show Starring Jimmy Fallon', Selena said: "We had to do a lot of promo for the album. So I woke up, and I was very confused on what was happening, on where we were going, because it seemed kind of far.

"So, I'm kind of a little grumpy. I'm, like, tired... I said, 'After this shoot, I'm going to go hang out with my friends.' And he starts, I guess, going, 'Okay, sure. We'll see when you get here.' "

Benny added: "She almost didn't even come. She was like, 'I really don't feel that well. I think I'm just going to stay home today. Can't we just make up the shoot another day?' And I was like, 'Uhh...' I'm trying to figure out a way to do...

"First of all, getting engaged to someone is the craziest thing in the world.

"It's like, right before you're going to tell someone you're going to be married to them forever. They're like, 'Show me how good you can lie to me.' It's the hardest... She was just upset with me because the day before, I was making bad lies."

In the lead up to his proposal, the 37-year-old star admitted it was the "scariest week" of his life because he was so paranoid about the engagement ring he'd bought being discovered.

He said: "It was in a box, and I had it hidden in a bag that I thought no one would go in. It was the scariest week of my life."

Benny said: "We're definitely not planning exactly at this moment, but we do want to make sure that the music's good."

The couple recently explained that Benny became the 'Only Murders in the Building' star's "personal journal" while writing the album.

Speaking on Spotify's 'Countdown To I Said I Love You First: Selena Gomez and Benny Blanco In Conversation', Selena noted they would chat in the mornings but never had a conversation about the record.

She added: "It was very, 'this is on my mind,' 'what is that,' 'how does that make you feel?' kind of thing."

Benny admitted: "Yeah, I felt like your personal journal.

"I was just, constantly writing whatever you said, wherever we were.

"Sometimes you'd be saying something, like, really important, and I would - I didn't know if you even realised - but I would open my phone and be like, 'F***, that's such a good line for a song.' "