To, be honest, Trenderhoof didn't actually look that promising. Rarity was already let down by Blueblood, and if she were to get a mate, it might change her character status completely. And it would be a bit odd, I mean, despite our fan community, little girls still watch it, to show the 'coltfriend and marefriend' stage to the younger audiences might grow some parental complaints...
The lines in this episode were a bit ...off, and trenderhoofs personality, even though he's 'the most interesting pony in Equestria' was a bit bland. And that poem he said in front of rarity; can any of yous, even though you made up the perfect poem to end in 'rarity' say that and feel like you didn't get an F in poetry or break a mares heart?