If you have children together, there is a statutory mechanism to deal with custody and parent child contact issues, and child support. However, before there are any court orders, the mother is deemed to have custody of the children. If the parents are married, both parents have custodial rights until there is a court order.
In addition, if you own property together, there is no equivalent mechanism to the divorce statutes for dividing the property you have acquired together. You would have to file suit in Superior Court, not Family Court, to obtain relief, and the legal issues could include property law, promissory estoppel, joint venture, partnership law, quantum meruit, implied contract, etc–complicated legal issues that can be difficult to prove.
Moreover, in divorce cases, there is an interim order, ordering both parties not to transfer property until the court can make decisions, or the parties agree. There is no equivalent automatic interim order in Superior Court.
Finally, there is no provision for spousal maintenance if you have lived together. So even if the parties have lived together for decades, and one earns a great deal more than the other, the party earning less cannot obtain any spousal maintenance.
So, if you are living together, and are acquiring substantial assets, it is a good idea to consult an attorney to help plan for what will happen if there is a separation.