These days, many people are afraid of getting married because of various reasons.

I was just having a thought, what if a couple live together and go through their day like a married couple without having to tie the knot?

Couple would worry less about divorce + breakup + split assets, where they can just breakup without bearing additional hassles.

Pros: Don't have a worry about divorce, lesser commitment and responsibilities to bear
Cons: ? (feel free to share in comment)

For the sake of the simplicity in this discussion, let's exclude the factor of religion, we can take atheist as a good example.
Comments pertaining to religion will be removed.

In a nutshell, would it be possible for a couple to live together, have children together and getting old together without signing paper?