You can post 3 day notice when ....

(1) when they paid rent late
(2) when they failed to pay late fees
(3) when they owed back rent
(4) when they get a pet in violation of lease agreement

You are running a business, not a charity. Why do you have to be friends with them?

That being said, I heard it is very difficult to evict tenant's in California. Go to 投资理财坛问其他加洲地主有什么经验。