What does it really mean when someone says, "You're their other half"?

[Anonymous]

My boyfriend has been being really nervous and fidgety lately. He started doing this after I accidentally saw a Tiffany and Company bag in his closet when he opened it. I told him one day I got my nails manicured he got weird by looking at nails being shaky nervous suddenly. Then later on he kept holding my hand just rubbing my ring finger on my left hand. It has been rather interesting and my boyfriend keeps claiming he hasn't gotten me a gift yet.

Then I went over to my SO's sister's for some food since she invited the family over. I went over there and she was super friendly along with welcoming to me as always. I said I am sorry if you just invited family to come over today, but I was already with your brother hanging out. She said, "You are always welcome since you are his other half." Then his sister was telling me I should come over in the summer for Margaritas with the girls and a BBQ sometime. Otherwise asking me if I liked something so we could all do a girls night involving; their Mom, Sister and maybe their cousin.

Why would his Sister call me his other half and why might they both be acting like this? Is it definitely possible they know something I do not?

[Discovery98]

His other half refers to the idea that you two fit so well together and have become so involved that you would be incomplete without the other like you are missing half of yourself. As for the weird behavior it is quite possible he plans to propose soon. He doesn't want to tell you he actually has the ring because he is saving that for the proposal. Worried when you noticed a gift bag that just may have that ring hidden in it. And rubbing the very finger he would be sliding it onto, possibly part of the behavior around your nails is he's worried about breaking them trying to put the ring on when he's nervous. I can't guarantee he is planning to propose but if his family has started calling you his other half it's probably because that's what he calls you around them indicating a very deep bond. Combined with his other behaviors there is a pretty good chance he will propose soon. Be on the lookout for further signs.

[pshi25]

Well it's a common phrase once you reach a state of acceptance with SOs family/friends. As for the fidgety etc, I don't know the time frame or anything, but could he possibly have his mind on a proposal? Sounds to fit the actions.

[shadowlegend]

That's just what people call other people's partners, their "other half", the other person in the relationship, half of the people in the relationship.

[Phoenix98]

It's like when someone says those two are like two sides of a coin it means you fit together basically.

Two sides of a coin
Yin and Yang
etc

you fit together and compliment each other.

[Anonymous]

It means that you were ca-joined twins.