Rumple knew Regina would be the one to cast the curse. He also doesn’t seem to be the type of guy to be a) sociable and B) the type to teach someone magic unless doing so benefitted Rumple in return. Teaching Regina magic definitely benefitted Rumple. Also Rumple has been burned before by teaching someone magic (Cora), he’s not stupid enough to teach a load of random people magic, especially as they might try and use that magic against him.
he was teaching some other woman magic before Regina killed her. Wonder what’s up with that
"I could have the giant duck as my steed!" --Daniel Radcliffe
Keeper Of Tamara's Taser , Jafar's Staff, Kitsis’s Glasses , Ariel’s Tail, Dopey's Hat , Peter Pan’s Shadow, Outfit, & Pied Cloak,Red Queen's Castle, White Rabbit's Power To World Hop, Zelena's BroomStick, & ALL MAGIC