Shawn performed songs from his new album at the Red Rocks Amphitheatre in Colorado, and opened up in a stunningly honest way, saying, "The real truth about my life and my sexuality is, man, I'm just figuring it out like everyone. I don't really know sometimes and I know other times."

Mendes, who was recently linked to both Camila Cabello and Sabrina Carpenter, went on ... "I think it's kind of silly because I think sexuality is a beautifully complex thing and it's so hard to just put into boxes."

He wasn't done explaining how the gossip got to him and how the jury is still out ... "It always felt like such an intrusion on something very personal to me, something I was figuring out in myself. Something I had yet to discover and still have yet to discover."

Shawn told the crowd his song "The Mountain" was a way of explaining his journey ... which he then performed.

It was a cathartic moment for Shawn -- clearly -- saying, "Writing this song felt really important to me. It felt like a moment where I could address it in a way that felt close to my heart. I'm just speaking freely now because I want to be closer to everyone and be in my truth."

As for the lyrics, well, they're revealing ... "Some days I have a change of heart / You can say what you need to say / You can say I'm too young / You can say I'm too old / You can say I like girls or boys / Whatever fits your mold."

The 26-year-old has clearly struggled with his sexuality. When he was 20 he told Rolling Stone ... "In the back of my heart, I felt like I need to go be seen with someone like a girl, in public, to prove to people that I'm not gay," adding, "Even though in my heart I know that it's not a bad thing, there's still a piece of me that thinks that and I hate that side of me."

There are lots of artists who now come out as LGBTQ, but not many who explain they're not sure and trying to figure it all out.