I couldn't agree more. I find that sort of thing perfectly healthy. Moreover, I think innocent crushes, in general, are healthy for relationships. But I do listen to ladies talk, and you're right, this sort of thinking stems from a lot of insecurity.

I don't think it's really the question of "what if Scarlett runs into my partner on the bus" that bothers them. Not really. Because as you said, that would be ludicrous. It's the thought, or rather, the knowledge that they've got flaws (like everyone) and that their boyfriend sees them, I guess.