Should my partner pay more money towards monthly bills?

[SandraM12]

I'm a divorced mum with 16 year old twin boys who live with me. I get nothing from Child maintenance (exhausted all avenues!) and the boys rarely see their dad. My partner has lived with us for 8 years - I own my house (still have a mortgage) - he has his own house that he rents out. He has 2 grown up daughters - and 2 grandchildren.
He pays 30% of most household bills that he uses (not mortgage and insurance) - food, energy, council tax, etc. We split pet bills 50%. He pays 50% of boys' phones as a kind gesture. I pay for ALL of the boys' other needs. They have part time jobs.
Because of my partner's wage adding to household income I don't qualify for Universal Credit.
I earn £34k and he earns almost double.
Should I be asking for more than 30% / some form of rent / extra contribution - as my money is running out and he manages to save each month?
He helps a lot with DIY in the house and is more of a dad to the boys than their dad ever was, but I wonder what people's thoughts and suggestions are please?

you say he earns almost double. what does he do

He should be paying 25% of bills and food.

No rent, he isn’t a tenant. It’s always advised on here not to contribute to another person’s asset.

I would expect him to pay for any treats, like meals out or takeaways

I'm not but they are her responsibility not his. So he shouldn't be paying anything towards their upkeep.