Help! Understanding of Co-ownership payment allocation

[Anthony Maffesoli]

Hey BP community!

First post here. I currently co-own 2 different properties. One is my primary which I live in with my girlfriend - I'll call this property A. The other I co-own with a good friend - I'll call this property B. Property B,  my co-owner lives there full time while I live in property A (he has no affiliation to property A).

My question is, how should I view the monthly payment breakdown of property B (further details below)?

Currently, my friend and I split the monthly mortgage payment but he pays all utilities. If a major expense comes about (i.e. roofing repair, hvac, etc) we would split that as well.

I don't particularly want to sell my share of this property as it has appreciated quite a bit since we've initially invested and I'm hoping I can eventually get him moved out to turn it into a full-time rental property.

Our current mortgage is a 30 year conventional locked in at 2.75% and the monthly payment is roughly $2000 ($1000/person).

Would it make sense if the co-owner paid rent and then we split the difference on anything outstanding that doesn't cover the monthly mortgage (mortgage is 2k/month. he pays rent of 1k and then we split the remaining 1k 50/50)?

I'm hoping to branch out into additional investment properties but the $1k/month that I'm seemingly throwing away makes this difficult.

I thank you all in advance for your thoughts and feedback.