Are these signs of attraction?

So I have a friend that’s basically one of my best friends. And whenever I’m around this friend we’re always laughing, always having a good time. This is the hard part, my friend has a significant other, but even before this friend was going steady with someone we always had this “attraction” I guess.
Idk if how we act towards one another should be called “flirting”? Hmm. How can I explain. On a scale from 1–10, I think we flirt on a level 3.
Here’s an example:
We went to the movies just to watch a movie and spend time with one another. Close to the middle/end of the movie, my friend wanted to talk about my love life. This friend would just give me this look and I’ve gotten this look before. It’s that look where the eyes are just so soulful and they look straight in your eyes & you can’t help but smile on the inside. I hate it because I’ve actually liked this friend before & every time we’re together I feel like I like this person even more. I mean I’ve read articles online about body language, but I just don’t know. So we’re whispering, but this friend is like really in my personal space while we’re talking. This friend would ask me a question and I would answer and they would go back to looking at the movie and look back at me, and our eyes would meet once again. Ugh! What do I interpret this as? When is it safe to bring up this thing I feel between us? I haven’t told this friend that I’ve liked them before, I’m waiting til they go off to the military to tell them. Should I also bring this up?