High functioning but suicidal

It doesn't make sense to me. How can I live a functional life but want to die? I've been dealing with chronic suicidal ideation and depression for a long time now.

I'm functional enough to appear normal to other people. My friends, family, and partner, none of them would suspect I would kill myself, I think it would be a shock to all of them if I died.

I laugh and seem happy but it's for the most part a mask. It's rare for me to genuinely be happy.

I always pictured someone severely depressed or suicidal to be obvious, like you could tell by interacting with them.

I think I've gotten better at masking. I know last year it was obvious enough that I was in such a bad state that my coworkers were asking if I was genuinely okay. I learned to hide it better so I don't bother anyone with these things.

I don't know how much longer I can keep this up. I got off a call with my partner and I seemed happy, but I still don't want to be here. It's like I'm searching for "home" yet I'm already home...I can't explain it any other way?