Q: What can a boyfriend do to help comfort his girlfiend on her period?
A: Treat her like a velociraptor. She is smart. She is fast. Make one wrong move and she will slice you open with her 6" claws. She can smell fear. She is the Alpha and the Omega. You hear her walking around, you stop moving and you stop breathing until she passes. Your best defense is to run and get as many shiny items between her, and you.
Remember, they know how to open doors. Good luck.