Being the only human in Equestria ain't all that bad, but having an overly affectionate, naive, older mare as a caretaker isn't the easiest thing to deal with...
Humans aren't nearly as robust as ponies. Simple gestures such as hugs, pats on the back, and hoof bumps are all well and fine when it's another pony on the receiving end. With a person a fraction of their mass, ponies forget how fragile others are
Ocellus and her friends only planned to sail to Manehattan for their final project. They never imagined a storm could take them... a little further than that.