Nahhhh.
Some people that suffer a major setback will be affected very negatively for awhile.
The "always happy" people will be affected the same momentarily, but pivot it in the best light possible, to dampen the impact on their mood. They are still slightly less happy, disappointment is a very real emotion. And while having a positive outcome on as much of your life is the most healthiest way to live, they are lying if they say they stayed 100 percent on the happy meter through those times.
These the type of people that exit relationships like it's nothing, never give themselves time to reflect or grieve, then develop nasty traits that ruin them years down the line because of unpacked baggage.