The most accurate description of daily prison life is the movie Groundhog Day. Every day is identical to the one before it. Same wake-up time, same meals, same faces, same walls, same routine repeated without variation for however long the sentence runs. The monotony is the hardest part for most people, more than the physical environment or even the separation from family. Time moves differently inside, and the sameness of it is something you have to actively fight against to maintain your sanity.
On the question of telling a guard about a situation, the answer is that the code around this is absolute and universally enforced inside. Informing on another inmate or passing information to staff, regardless of the reason or the circumstances, carries the label of snitch and that label does not come off. The prison population operates on a social code where loyalty to other inmates over staff is non-negotiable, and violating that code has consequences.
The saying that snitches get stitches exists because it reflects a real dynamic. An inmate known to have talked to guards faces retaliation for the remainder of their sentence. In serious cases the only options are protective custody, which is essentially solitary confinement, or a transfer to another facility to escape the reputation. Neither outcome is comfortable.
The practical reality is that if someone witnesses something serious and needs to report it for their own safety, there are more discreet channels than going directly to a guard on the unit floor. An anonymous tip, a written note, or a request to speak privately with a counselor or the warden's office creates some distance from the perception of open cooperation with staff.
The code is real and the consequences of ignoring it are real. Anyone going in needs to understand that from day one.