Helping to silence decades of speculative whispering, Prince Albert II of Monaco, 49, has, in recent months, been increasingly expected to marry his South African girlfriend, former Olympic swimmer Charlene Wittstock, 29. That is until she failed to show up at the prince’s side during the royal line-up today, Monaco’s National Day. Ms. Wittstock has been at Mr. Rainier’s side off-and-on during public events since they began dating, sending Monaco’s rumor mill into a dizzy tailspin. Her presence on the balcony today would have, according to some royal watchers, all but solidified Ms. Wittstock’s future place on the principality’s throne. Now, however, Mr. Rainier’s matrimonial outlook is rather unclear.