I can't speak for all but my experience and most cases I've seen here is taht the shared expenses is not in itself a major barrier for most genuine couples residing together. It can be for those living apart and with other red flag issues with their files.We always tell the truth. Yeah, we have shared expenses. Couples usually do have shared expenses. I could explain it in the letter and get support letters from friends as well.
We will cross that bridge once we get there. It is not rocket science.
More important for those who are applying as common law with only barely meeting the twelve months and other issues (like not having a lease in both names, etc) - but here the issue is more demonstrating the common law requirements, and putting too much weight on joint expenses in the absence of stronger evidence of living together.