The Friendly Sacrifice
Being a true friend requires sacrifice.
In a rock-solid friendship, you may be asked to give up your desires for your friend's needs. Your friend may need you when it's not so convenient for you, like in the middle of the night.
In a rock-solid friendship, this would involve sacrificing the comfort of a good night's sleep in a nice, warm bed in order to be there for your friend.
But that's what friends do!