Dear one and One and only

One and only and dear one are semantically related in sweetheart topic. In some cases you can use "One and only" instead a noun phrase "Dear one", when it comes to topics like darling, person whom another loves.

One and only adjective - Eminent beyond or above comparison.

Dear one and one and only are semantically related in sweetheart topic. Sometimes you can use "Dear one" instead a noun phrase "One and only", if it concerns topics such as darling, person whom another loves.