Moving in with his family. Is it a deal breaker?

My boyfriend and I have been together a year, live separately, have our own homes, both mid 30s. We have been having conversations about timing for marriage/kids and what we want from the relationship because we aren't getting any younger. BUT his mother has just asked him to move in with her to help her out as she is on her own. I don't think that is a reasonable request. His other siblings live with their partners so she hasn't asked them and I don't see any of them volunteering to move home. I feel like it's just setting our life back even further and I am worried his mother will just be more co-dependent than she already is (she is at his house almost every day). Don't get me wrong, I get along with the (future) MIL, but I also think she can get by without her 35yo son living under the same roof and I don't see how we can let our relationship progress and flourish while he is living at home with his mother. How do I broach this with him without causing issues with his family? Or is this a deal-breaker/red flag to walk away from?

Moving in with his family. Is it a deal breaker?
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