There is no such thing as a common-law marriage, just because you have lived together for many years does not mean that your relationship has the status of a legal marriage.
There is a principle of universal partnership where it must be proved that the couple intended to deal with all their assets together and share the proceeds equally. This is very difficult to prove. If you live together you need to have a clear and simple agreement regarding the following:
Living expenses -who pays what?
Movables bought together-who keeps them?
What happens if you want to separate?
Do you have a will regulating what will happen if one partner dies?
If there are children involved- you have to have parenting plan.