Spike's heart still belongs to Rarity. But she's kept him in the friendzone so long that he's probably open to a reasonable alternative. Until now, his flirting with Applejack stayed just below my radar. But looking back, from the almost “accidental” kiss in Dog and Pony Show to the massage in Spike at Your Service, it now seems painfully obvious. Check out this little clip. Sadly, I don't even know what episode it's from.
http://www.youtube.com/watch?v=5pkVC2JWTgU
Sound effect gag aside, what is up with that? I imagine AJ is exaggerating a bit, but why would Spike hug her repeatedly if he considered her just another older female pony friend? “Hoo there, loverboy,” indeed!