It still sounds like a recipe (see what I did there?) for disaster.
As Andy said, 50/50 is dangerous. I know you are saying 51/49, but in real terms, it means no real control, anything under 75% means everything has to be agreed on and if there is a difference of opinion in the future (eg business grows and the catering outgrows the building), then it can cause bad blood. The best of friendships will be tested to the extreme when it comes to business.
It sounds like the bar owner is getting a steal. Providing building space for a building he already occupies, providing catering for a business he is already running.
Renting office, building space is just normal business overhead and not worth giving away half your equity, particularly if you diversify and outgrow it in the future.
Providing catering to a bar is just a contract? Why not do it on that basis? Then she is free to pursue any business interests as she see fits.
I'm sure there is a to more to it, but on the information you have given, it makes no sense to give away half of your business and control.
Giving equity away at the beginning of a business journey may not seem such a big deal, but you try and buy it back 5, 10, 15 years later. Or imagine if you need to release some equity to bring in a business partner as the business expands. Then all decisions will be vote by committee with no one in charge.
Tell her to hold on the equity. If she is friends with the bar and business owner, then do a great deal, pay for rent and sort out a proper contract to supply food. Everyone wins and life is less complicated
IMHO.