J.S.
He has every right to keep his adult children as his beneficiaries on any accounts he has for insurance or mutual funds or annuities or any other financial accounts. Even if you were married he wouldn't be required to put you as a beneficiary. Perhaps he feels an obligation to his children to make sure that upon his passing they're provided for so that they can pay for his funeral and all associated costs.
And as long as you're not married and your name is not on the title of the house, his kids can do whatever they want with the house.
He has every right not to want to get married. But here's the thing. Why in the world are you with a man who refuses to commit to you in the way you need him to? Why are you with a man who you feel isn't making you a priority? And why in the world do you have him as a beneficiary instead of your MINOR children?
Stop making this guy the center of your universe. You're clearly not the center of his. I think you need to adjust your priorities and put yourself and your kids first.