Spike has long felt something missing in his life. More particularly that despite being a Baby Dragon he has never had what most would consider a childhood.
Spike finds solace in surrendering himself to juvenile needs and wants that Twilight does not approve of. This leads to a fight with Spike storming out. Eventually coming across Rarity who is more than willing to give her Spikey-Wikey what he so desires so long as he does not share her feelings and their actions with any pony else.
In the end Spike takes comfort in how the one who has the Element he truly represents does love him for who he is.