NB: I admit I lean more towards the cynical end of the spectrum and this will affect my perception.
We’ve had a pandemic, a war, and Austerity On Steroids is on the way.
Since it’s only been six months my instinctive reactions is
A) He’s felt like life was on hold for too long and has been pandemiced/warred into a very “seize the moment” mindset, cos you don’t know what tomorrow may whack you with next.
B) See above, but the fuel is more about Austerity on Steroids looming. And it’s you or a housemate to help lower the pain of bills, rent, mortgage etc. You being a far nicer prospect than a stranger.
Personally I’d ask for a trial run period were you are a guest. Stay a week, home for a week, stay for 2 weeks back home for a week. Until you work your way up to a month, then a week or so off. Holding that pattern until both of you are completely sure the practice is as great as the theory. It’ll give you both a chance to feel the difference between living together and not. Work out which front door opening feels like relief, which front door you are exiting makes you feel a bit “ouuuf”.
In that period you both have the time to work through all the stuff people really should set out before they commit to each other. Because that’s the stuff that will decide if this has legs as a long term thing. Or one of you is sleepwalking into partnership that looks like it could implode under the stress of life stuff, world disaster stuff, kids, job loss, bereavements, illness etc.
It’s not that things can’t work out despite it happening very fast. I know several long term (20+ years) couples who got things off the ground quick smart. It’s just these are not normal times. And not normal times can make even “in more normal times” lovely people make less than ethical choices they wouldn’t have contemplated in different circumstances.