"He was a lot of things to me" "The only conclusion was love"
I think that line from Belle in Skin Deep was more a statement on how he had love, true love, but he’s throwing it away for power (gah, just like Cora did to him. Jane Espenson, you sneaky woman). So now he’ll be just as lonely and miserable as before but with the reminder of cup. And she also tells him that he’s going to regret it. And we can see he instantly does after she leaves and he closes his eyes in pain. I don’t think that particular line has anything to do with this.
However, Rumple is probably up to something, but I don’t think he put the idea in Regina’s head. In the promo he tells her “why don’t you just give up this revenge?” I think he wants the blood fighting to stop but he doesn’t want to actively involve himself because then it gets messy and emotional, and Rumple doesn’t know how to love anyone outside of Bae and Belle yet. He’s still learning how to love those two and to add more to his life is way too hard for him, thus why he reacts so badly to Henry in The Queen is Dead, telling him “it’s your fault” when he got stabbed. He likes Henry but he wants not to. I do think Rumple has some sort of plan that we haven’t been made aware of yet, but I’m not sure it has anything to do with this curse.