Okay, fifty year old asshole here. I've danced the dance more than a few times.
Don't waste time fucking around. You have the feeling, you be up front, honest, and let whatever happens happen.
A real friend? Trying to go romantic and failing won't change a thing long term. A real friendship is too deep to destroy by just not working romantically. And if it isn't that deep a friendship? Then something would have ended it eventually.
Now, if things don't work, but only one of you thinks that, it can take time and work to move past, but it will if the friendship was real in the first place because you'll value each other more than the failure can break.
You also have to be prepared to hear a no, and then learn to move past the no. If you can't, then chances are it wasn't that good a friendship to begin with.
There's going to be nerves, but you just open up, let it go, and let the other person respond. Don't do any big gestures, no movie crap. Just be the person you are and talk about it.
Me? Once I got past the whole fear of rejection thing, it was always easy to just say "hey, we're pretty close, and I'm feeling some extra love here, beyond the friendship part of things. It seems that's reciprocated, so how about we try this? Let's do a formal date and see if that gives us a jumping off point."
The conversation goes from there to whatever the next thing is. Sometimes it's a no, and solutions it's a yes and things don't work. But sometimes it's a yes, and things do work.
Right now, me and my wife (that started as friends, and didn't even realize we were moving into romance until I told her I loved her and things moved kinda on their own) have occasional dinners with three of my exes that are still good friends. And I'm still in contact with others that aren't close enough location wise to have many visits.
Tbh, the only exes that I'm either not still friends with, or wouldn't be if we were in the same location, were ones that didn't start as friends.
Seriously, the next time y'all are going to be together, when there's a moment that the feeling it's going somewhere, say something.