Military life is hard. Even non-combat deployments are incredibly stressful. I know so many guys who broke up with their partners within a month of starting their first roto. It's not easy to be away from your friends and family for extended periods of time, and it's not easy being around the same coworkers 24/7 in a god damn pressure cooker with no privacy or alone time.
For the sailors on the Lincoln, it's much, much worse. No internet because they're under combat conditions, moldy showers, not enough food, broken down laundries, failing infrastructure... It's a nightmare. What these guys are dealing with is not normal, and no sane military would have kept this deployment running as long as they have.
Mental resilience is a huge component of being a part of any military. It's the single most important skill a soldier, sailor or airman can have. Being a good shot or able to ruck thirty miles are useless if you crack as soon as the shooting starts. But mental resilience can only carry you so far. This situation is well beyond what anyone is trained to deal with.
But unfortunately the US Military is being run by a draft dodger and a guy whose service record consisted of throwing keggers, so "mental health" is something that only happens to queers and liberals, and they probably think that the guys jumping off the deck are paid by Soros. This is only going to get worse. Apparently, the Lincoln is being given 3 days of R&R and then it's back to the endless hell with them.