I have, you have, we have

Something really meaningful happened to me a few days ago. It made me realize some things about myself.

A friend of mine and I went for a weekend to the capital city of the neighboring country. She stayed at her friend’s place and I stayed with mine. But before I met up with my friends I stayed with the friends of my friend. Those friends have been married for a couple of years. The wife is not into anything related to the modern technology. She hardly uses emails let alone facebook. They have a computer. There was a connection problem and she obviously didn’t know how to fix it. I thought it was not her computer. I asked:
- Is it your laptop?
(a short silence)
- Your husband’s? – I continued
- No… It’s ours! – she said with a sincere smile and a bit of surprise on her face.
And then I realized. They had been together for years so why would the laptop belong to any of them only? It was their common property and it was obvious. As much as I am into relationships (especially mine) I have no concept and idea whatsoever on merging assets. I don’t know how you do that. It is so weird me for to live in a flat that belongs to two people and not to one of them. It is so awkward to posses the common things. It is so normal to lend/borrow some money and then give it back/claim it. I cannot understand how it works.

Is it possible to learn that? Does it come with time? Do you need to have some agreements?