You say he was only living with you 3 to 4 days a week. I would assume he had other premises he was living in as well.
Were you also paying for the other premises?
The time you are together will assist in proving you were a de facto couple, because you were together for more than 2 years.
The next issue is financial contributions to the building up of assets.
To have you understand a little bit more when the courts and the law split properties between de facto couples and married couple they apply the following 4 steps.
Step 1: Determine what the assets are and their value
This will include all assets and their value as at the day that you are dividing them. It does not matter whose name the assets are in, they will form part of the matrimonial pool. Superannuation entitlements are also included.
Step 2: Determine what contributions you and your spouse made towards the assets.
This includes a consideration of both financial and non-financial contributions. Consideration is given to what assets each of you brought into the marriage as well. The weight given to your initial contribution will be dependent upon the length of your relationship. The longer the relationship the less weight given to the initial contribution.
Step 3: What are each of your future needs.
Consideration is given to your respective ages, your comparitive income earning capacity as well as other factors.
If these things don't balance equally for each spouse, then an adjustment is made in the percentages.
Step 4: Make an order that is just and equitable between both spouses
This is what the court will get if you put on an application.
I cannot tell you an exact percentage you are entitled to that if your contributions to all the assets of the relationship is not there it will be difficult.
If you are paying all rentals food for both of you and he was not paying any rent anywhere then you have a claim.
You will need to speak to a solicitor the practices in this area and provide them with full particulars of the relationship as well as evidence of payments and they will be able to give you a more detailed advice.
I'm happy to provide you with the details of the Law Society's that you can get a referral if that is what you would like.
But you understand what you need to be able to show?