My boyfriend is always taking his phone everywhere. Is this normal?

My girlfriend was telling me that her boyfriend she has been living with takes his phone everywhere with him. She's very upset because he will spend a lot of time in the bathroom smoking and supposedly being obsessed with a game? She's thinking he might be talking to someone else and using the game as an excuse or trying to escape from her? She said their relationship "sucks" and she doesn't know if it's all in her head because she is mad at him about things or if she should really be concerned.
My boyfriend is always taking his phone everywhere. Is this normal?
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