Not sure about your state laws, but here in Illinois, unless you are legally separated, your spouse has a right to everything accrued during your marriage...together or apart. Check on your state laws.
Now in PA anything after date of separation ( I left in may so anything he bought in june I am not entitled to) is NOT considered marital asset.
Also in most cases it is 10 years of marriage and then he is entitled to a % of the retirement