So my idea to end the partnership but preserve a friendship was to list our properties. 

I'd also revisit the conversation of how you will maintain your friendship should anything go wrong.

This can end friendships and cause more problems.

I want to be fair, and also want to keep our friendship and hopefully more deals for us! 

So I definitely understand that I need to stay professional and we have been professional towards each with some friendship forming in this case based on the circumstances.

It's a quick way out of a friendship.

No two circumstances are exactly alike, but I don't think that it's generally a good idea to rent to family or friends, for reasons described above.And, I've learned to avoid social media "friendships" (via Facebook, etc.) with my tenants.

They have their friends, but friendship may wear thin living together or they can come up with new boy/girl friends, etc. etc. etc. 

he has gone through so many friends so doesn't care if a friendship ends.

@John De La GarzaFirst - don't do business with friends unless you no longer need his friendship.