Assuming they work full time, that is pretty average. The old "30%" rule is that you should spend no more than 30% of your pre-tax wages on rent. Your friend is spending just over a quarter post-taxes.
Something about this still seems to be imbalanced.. and 45/160 is 28%, just below this threshold you've referenced. My intuition says something is wrong here.
Either I missed or was added in an edit the bit about having roommates. That's definitely absurd. I was paying that amount for an entire house in a nice suburb maybe 8 or 9 years ago. Even with only one roommate paying the same amount, they are together paying way more than my mortgage for a house in the country with 5 acres of land and waterfront along one entire side.
I imagine they're in a high cost of living area, where tons of other people want to live. If that's the case, it probably shouldn't be any surprise that in a supply restricted market, the prices are also very high.