Mum financially dependant on me?

I'm 26 and I live alone with my mum. We both pay the bills. My mum is on benefits due to severe back problems and therefore if I was to move out, she would also have to leave and find another place to live. We live comfortably, however without my financial support she wouldnt be able to afford a place to live on her own. Im in a relationship and looking to get married next year and my partner is okay to move in with us for the time being however eventually we will need our own place. He has his own mortgage to pay and his mum and brother live in that house, and he lives an hour away. Being of an asian background, his family arent very happy with him moving but accepting of it. I am concerned though that his family will affect our future marriage when he does move out as traditionally the girl moves. I just feel stuck as I feel i have a duty to support my mum as she did it as a single parent. Both me and my partner have a great relationship with her as she never invades our privacy. Any thoughts? Thanks guy/girls!

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