None of the consequences of a marriage automatically ensue if partners simply live together. Thus life partners do not automatically have the right to share in the other's property during or after the relationship. Life partners are able to use contracts to achieve a measure of protection as against each other as well as against third parties. They may for example purchase assets jointly, or jointly enter into lease agreements, credit agreements etc. in such cases the terms of each contract will determine the rights, duties and obligations of each of the life partners. Usually the life partners are the joint owners of the assets acquired and joint debtors in respect of the obligations incurred.
Where the life partners are the joint owners neither of them can exclude the other from using or controlling such assets. Unless they have entered into a partnership agreement either of them may alienate his/her own share of the jointly owned assets without the other's consent. If the life partnership breaks down and the life partners can't agree how to divide the assets either of them may institute the action communi dividundo in which event the court will then appoint a receiver or liquidator to divide the assets.
It is best that life partners regulate their rights in terms of a cohabitation agreement. In this agreement they may for example undertake that they will maintain each other while the relationship lasts, agree to posy separation maintenance, regulate ownership of the property each of them owned before the start of the relationship, agree on property acquired after the relationship started, agree on occupation of the common home during the relationship and after termination and so forth.
Partners living together should enter into a cohabitation agreement. I have dealt with numerous disputes over the years where partners terminated a relationship with or without an agreement in place and it is usually where there is no agreement in place that the turmoil starts.