I've never heard of them until now. I don't know if it would make sex less messy, but I bet it will be a mess when you remove it. 
I'm sure something like that a guy will be able to feel. I don't know if it'll hurt you, but I think you would feel it being pushed.
I do hope he wears a condom, though. That cup doesn't seem to be a form of contraceptive.
If you don't like the blood, why not just wait when your period's over?
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No matter how gifted, you alone can not change the world. - L
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