You're right that it's hard for someone to know our boundaries if we don't tell them. But you're also right that those boundaries should not be assumed. Those things can be true at the same time, and neither invalidates the other or how you're feeling about this whole situation. Too, I'd add that you didn't provoke what he did; knowing someone is interested in you and spending time with them isn't consent to sex.
With those thoughts about being uncool or complicated if you didn't agree to sex, were those things he'd expressed to you before or during all this?