Momentum comes and goes like tidal waves. Sweden was struggling this year in the round-robbin of the White House tournament invitational team tournament in Holland. Take a seat.
You pick up (imps, all white) :
Your Russian RHO opens a multi 2D (weak 2 in either major; could be 5) and you pass (I wonder if Lauria would slip in 2H? ;). LHO bids 2H, pass or correct, and partner overcalls a natural 2NT ("16-19"). What would be your choice?
Passing is not an option, if anyone was contemplating that for even a split second, so it's a matter of which game. Just raising to 3NT has a lot going for it; you know partner has the ace of hearts and your spade length also favors notrump. A weak doubleton may be a liability if that suit is led but the lack of aces/kings may mean that 9 tricks is a better shot. Remember that for 4H to be a better contract than 3NT, the major suit game has to produce at least 2 tricks more (10 vs 8).
A reasonable line of action is to check for a primary fit in H and otherwise play 3NT. That's was the choice of the Swedish South and a 3C ask fetched 3H showing 5-card H's! The euforia was short-lived, as this was the full deal:
2NT was a practical bid, under pressure, with the North hand. 4H was quickly down after a minor-suit lead and spade shift when North covered the queen (nonv the spade suit could easily have been 5-cards) and 3NT proved to be the only making game.
I'm sure South was kicking himself as raising to 3NT probably was his first thought. And, I think he would have if they hadn't been 'out of sync'. Momentum, real and perceived, is a powerful force.
Sometimes you just can't seem to catch a single wave.