People here aren't understanding that the Mane 6 are maturing, and usually, in life, when you mature, you find a mate. I know it must feel a little weird to see someone you have seen go without a relationship for the duration of the show suddenly hop into a crush with some random young man, but that's how life is. I believe that the Mane 6 wouldn't stay single forever, after all.
Me? I think Flash Sentry is cool, although he is very, very cliche.