I'm not sure what you mean by arbitrary. To me, an arbitrary choice would be pursuing a relationship with a random person for no reason at all. You have reason: you're attracted to your friend, and you think she might be attracted to you. That sounds like a perfectly logical reason to pursue a relationship.

But it's up to you, OP. Do you think that if things change unexpectedly, you'd regret not giving it a chance? What are the best case and worst case scenarios if it worked out or didn't work out? Could you guys still be friends if it didn't?