Conventional Loan Violation via house hacking?

[Grant Shipman]

I'm working on getting my first property under contract, and I would really appreciate advice on whether my plan would be violating the terms of the mortgage.

PROPERTY & LOAN INFO:

-Conventional Loan for a Primary Residence

-Single Family 2 Bedroom Home with a basement and an accessory until (360sqft tiny home).

PLAN:

-My partner will be on the loan (and therefore must have the house as her primary residence for 12 months), and we will build out the basement as her living space.

- Will rent out the rest of the house (2 other bedrooms and accessory until) via long term rent or Airbnb.

MY QUESTION

My mortgage lender is concerned that renting on the rooms to long term renters or Airbnb during the first 12 months may violate the mortgage agreement. I have researched everything I can on OO loans, and I don't understand their concern. Please respond with anything you think helpful. Thanks!