I'm with azif. My partner and I have a joint account and pay a set amount each month into it. We calculated the amount by totting up the mortgage + monthly bills, dividing that total by 2 and topping it up to allow some leeway. You could always try the same by weighting it slightly more towards you if her salary is significantly less than yours. As well as not really being aware of the montly bills all being paid, the leeway allows some build-up over time and we frequently are then able to buy joint stuff from that account including leisure things e.g. theatre, cinema tickets, restaurant meals, without having to further dip into our own accounts. Bear in mind if there are further interest rate rises, your own individual account could end up getting hammered.
We also have an additional monthly amount going into savings. Over the past few years that has been a godsend for e.g. holidays. We plan the holiday, and bingo - the accommodation, travel etc is all paid for straight off from ready funds. Though this year we're reserving it for a new bathroom - if we can EVER get any s*dding plumber or builder to get back to us with quotes.