Ok, we all know Crowfeather loved Feathertail right? But, what if when Feathertail died she was pregnant. It's a theory. Crowfeather did spend a lot of time with Feathertail on the journey.
Crowpaw spent all his time sleeping and walking with Feathertail.
Crowpaw was so in love that he changed his name to give memory of her.
Crowpaw was so heartbroken, I think he mated with Leafpool to get over grief.
Feathertail was a warrior, and Crowpaw an apprentice.
Crowpaw acted hostile on the journey when they talked about Feathertail X Crowpaw