What major life change? His engagement (it's been a while but as I recall, he was already promised the captaincy by the time of his actual wedding)? Why would it make sense to give him a ship when he was engaged to a woman on his current posting? It makes far more sense that he was occasionally offered commands we didn't see, and he finally decided to accept one. Does that really matter though? Assuming he requested a command, he got it, so obviously there was a command available for him.