As others have said: both work.That is, they are BOTH broadly correct for contemporary English usage. I believe James highlighted a technical matter. As a native English speaker who writes , however, I would say: "I´m happy that I´m yours and you´re mine."

Both seem correct to me! The 1st sentence seems to emphasize the fact that you are HAPPY to be theirs !

this is an interesting question. Technically the first one is not correct because you're using a coordinator "and" while repeating the subject "I / I am" so we need to have a comma " , " before the coordinator "and" - Example: I'm happy to have you, and I'm happy to be yours. Number 2 is totally fine and sounds way more fluent because we're not repeating our subject or the adjective, which we don't have to so that's nice. In fact we could abbreviate it even further "I'm happy to have you and be yours" so i dropped the second "to" as it was also repeated in both of our clauses. When we are connecting to independent clauses like this with a coordinator like "and" we don't typically need to repeat the subject (if it is the same subject) and we can even avoid repeating verbs or adjectives (if they are the same in both clauses)

Both are correct however, the 2 sentence avoid redundancy.

Hi Areum, they look ok to me, but grammatically I think they're a little bit redundant. Personally I prefer to choose one over another. For example: I'm so glad to have you I'm so grateful to be yours But if you want to put two sentences together I agree with what Alex had written, for example to change the sentence to be "I'm happy that I'm yours and you're mine". It looks more efficient.