Opinion please

So I have a complicated relationship with my stepbrother (just to be clear we have ZERO blood relation). We make out occasionally and we've definitely got a thing for each other but I really want to talk to him about it because I'm confused. We never talk about it and it sort of just happens randomly so I never really know what to think. I feel like I need to have a conversation with him about it and maybe just define where we stand so I don't feel so confused all the time.

Also before you judge me for this, our parents aren't even married but they live together. We aren't technically stepsiblings.