It would appear by your question that neither party has filed anything in court. If the marriage is over you should consider filing a Petition for dissolution to end the marriage. You should pay close attention to the date of separation. I am unsure by what you mean by gaining marital assets (taking assets?) You may want to consult with an attorney in your area before you take any action.
There is no such thing as "marriage defacto." There also is not a "divorce defacto." And it's not clear what it is that you want to do.
Presumably, you are married. Either by license or at common law (which is only recognized in a very few states and requires that both parties "consider" themselves married, as well as a few other requirements. There is no such thing as a "common law divorce."
If you are separated – and have been separated for a while – then the way in which the property that the two of you possess will be determined by the law of the state in which the divorce is filed. But you also don't provide enough information to know in what state that might be properly filed. If you both live in Ohio, then that is probably the appropriate place. But it's possible it might not be the right place.
You should immediate make an appointment with a qualified and knowledgeable family lawyer to review with that lawyer your specific situation. Only by doing so can you find out what you can – and can't – do and what are your rights, duties, and possible exposures.
This response does not constitute legal advice and does not create an attorney-client relationship. I am licensed to practice only in Kansas. Seek legal advice from an attorney in your state or the state in which your legal claim exists.
If you are married, then you need to file to terminate your marriage to deal with the assets of the marriage. Depending on the length of separation and the contact and support between the two of you will provide a basis for the division of the assets.
If you were never married, then there is no marital assets. Common law marriage in Ohio ceased in October 1991, so you had to have established the common law marriage prior to that date to be legal.
Talk with a family law attorney so you can provide more facts in order to obtain a better answer to your situation.
This answer is being provided as general advice only and is not to be relied upon for specific circumstances. By answering the question, no attorney-client relationship is created. As for any matter, it is best to seek consultation in person with an attorney who practices in the area of law in which you are inquiring.