My wife was the first partner I'd ever lived with (loads of house shares but never with a partner) and we moved in when I was about 37.
I was was very worried (we both were) about independence and space and stuff but actually it's mostly been easy although that doesn't mean there are no difficult bits. Definitely old childhood patterns come up, for me this is the first time I have made a family home to replace my childhood one and that's big. I'm not sure you can limit the risk by declaring it an experiment and planning an exit strategy, if it doesn't work out it's going to hurt experiment or not but the risk is easier to live with if you can both acknowledge it. The first night we sat in our newly rented flat full of boxes we were both terrified, I turned to my wife and blurted out, I'm scared!!!! and she howled back Me too!!! We both had a little cry, then a big laugh and opened some booze.
We have a rota for chores and we renegotiate that a lot depending on circumstances, we each do the job we are most fussy about. We have a joint account for the bills and food shopping but our wages come into our own accounts and then a set amount gets paid each month by standing order to the joint, (my data obsessed wife recorded all our spending for the first three months to work this out....) leaving us each with our own spending money in our own accounts. My wife ended up joining the same bank that my account and our joint account is at so we can transfer money about instantly if we need to. We also have individual and joint savings accounts, it's complicated but it works for us.
My life has changed out of all recognition, it's unavoidably a compromise from the total freedom I had as a single person. I don't feel my wife is the other half that completes me, or make me whole or that we are now one unit but that we are a commune of two individuals who have chosen to work together on life because we bring each other joy. I wish you the same.