Nail on the head there. I'd rather live with someone in a nicer area, nicer house, etc than both of us living separately in compromised homes. When he dies, then I'd reconsider if and when I had another long term partner, depending on our relative positions, financially, location, adult children who may want to live/stay with us (his or mine). To be honest, If I had a new long term relationship with someone new, and we "could" afford two homes, I'd rather have one in the UK and the other abroad which to me would be far better than having two homes close together in the UK which I'd find a waste of money and unnecessary.
My only problem would be if he had children still living at his "home" or adult children who regularly returned to stay at his home more than the odd night here and there or short breaks etc - if that were the case, I'd not want a "blended" family home and would prefer my own home - I just couldn't feel "at home" in someone else's "home" with their children also living there - it just wouldn't feel comfortable to me.
I have a life long friend who has a long term partner who has a couple of children, one still living at home in her 30's and the other sharing his time between his own flat down South and their family home. She won't live with him, won't even stay over at his house, as she sees it as his daughter's "home" and his son's "occasional home". So he regularly stays over at hers instead. They still go on holidays together 3/4 times per year (without his children of course) and go for weekends away etc. He keeps asking her to marry him, but she won't as she'd only marry if it was just going to be him and her in the marital home and doesn't want to marry and continue living separately. She has no kids of her own (never wanted them) and just doesn't want "someone else's" kids in the house she lives in either. They rub along very well otherwise, but it's just a red line for her. Luckily neither of them are short of money and can afford their own respective homes. And I tend to agree and see it the same way.