The In Your Blood singer was struggling with anxiety when he and Cabello first hooked up and he decided to keep her at arm's length, so she wouldn't witness his mental health issues.

"I went through a month where I couldn't really even communicate with her because I was struggling with anxiety, and I didn't want her to see me weak," Mendes said during an Apple Music interview with Zane Lowe.

"I was on the verge of ruining our relationship," he reflected.

But just before he wrecked everything with his Senorita duet partner, Shawn decided to open up to her - and now he's glad he did because she has helped him tackle his anxiety issues, having experienced them herself.

Describing the experience, Mendes shared: "When you come out on the other end, and you're like, 'Listen, I'm struggling here. It's hard for me to even say this to you'... and everything starts building and growing and getting stronger, and the roots fortify."

He went on to say he had learned to look after himself: "You cannot be the best version of a son or a brother or a boyfriend or a friend to anybody if you're not constantly there for you, and you're watching out for you, and you're checking in on your heart and your space and your energy."