s312

I am sure you meant 2018 tax return     Anyway for two people your gross income from 2018 already exceeds the 125% requirements so you should be fine.   Only Alaska & Hawaii have special income requirements.
 
https://www.uscis.gov/i-864p

No
 
Sometimes borderline cases (100-125%) get sent back for joint sponsor but I haven’t seen any affidavits rejected when the primary sponsor income-based meets the 125% threshold.