I don’t borrow or lend so $$ doesn’t hang over the friendship

I was pondering a favor a galpal extended, which I graciously declined because I don’t loan or borrow $$ from friends. She offered me an interest free loan for a $5,000 project. $5k for 24 months at the 12.5% my credit union offers would be $676.88 interest. At 4% (I wouldn’t consider zero %,) the interest would be just $210.99, a difference of $465.89. We have the same bank so I could schedule the payments to transfer automatically each month. When I write it all out, it’s just a savings of $19.41 a month and that’s not enough for me to warrant having anything hanging over our friendship.