simply because you offer doesn't mean
we have to take it.
Thinking we are ungrateful, you may be not aware
that enforced assistance is rather a burden, than a favor.
You better not ask why,
it's just a polite way of
saying the offer is not good enough, or needed.
If you just want gratitude or someone in your debt,
then you are not prepared to offer.
The gesture of offering already does you enough good in its own right.
So,be grateful when offering.