Honestly, Rumplestiltskin didn't want to free his caretaker. But there was a part of himself (which he wasn't horribly willing to acknowledge) that was beginning to care for her enough – not that he cared for her – that he might do it regardless. She'd said it herself; she wanted to see the world, not just his estate. He always reminded himself that, should he let her go, she'd only be allowed to return to the fiancé she'd admitted she didn't want.
Then Gaston showed up, and Rumplestiltskin was quick to do away with him… and his excuse to keep Belle around.