They may decide that your business is just too much work with no loyalty from you....

(you don't have to of course) Seller being a realtor; can cause problems: (may or may not be ethical) but they will stay clear of information otherwise known if you use your own realtor: (even if you "have" to use the seller as the representing realtor: still get "a realtor of choice " just to do the due diligence - and let them know that they will have your loyalty there after or when you sell it. - ask for previous rents: 1 year or more: I know its cash: but they should have receipts of payments and when exactly tenants paid (on time or not). 

It takes a rather strategic mind to see and understand that you folks are worth it for the loyalty factor: they have to understand that if they help you make a crap ton of money, you will make them a crap ton of money!

I've always ran my other businesses with this mentality of building opportunities for everyone involved and have found that has helped me build a strong team due to the mutual trust, respect and loyalty to each other.

Which means, a homeowner, who relies on information from their agent who listing their home, is often expecting that same loyalty from the wholesaler.

Our loyalty and duty is to our clients. 

Moving is expensive and is a pain so as long as you aren't too far off I'd be tempted to just thank the tenant for being great and let them know that this year we are keeping rents the same to thank them for their loyalty. 

That is what brings loyalty to our leads. 

How to get them, create loyalty and find the best ones. 

I'm sure they are afraid of your loyalty.