You're right, some people get lost when they pretend so much. But there's another cost that's often overlooked: if you always seem fine, people (family, friends, or partner) might turn to you when they have a problem, which creates a constant overload on top of the problems you already have, not to mention the dependency that can develop from always being the pillar that holds everything together. That happened a lot to my mom, who was the breadwinner, and it left her exhausted for years, causing her many health and psychological problems.
By always being the strongest, you end up becoming a shield for others, and often, unintentionally, you can prevent them from solving their own problems.
RE: Pretending to be Okay is a death trap, avoid it.