You were expecting fawning gratitude, you got “let me check out what I’m spending money I don’t really have” and you’ve given her no choice or say in the deal, just presented her with a parts bin (nice though it is) special.
She knows she can get a brand new bike, now she probably feels obliged to take a bike she doesn’t “really” want, and feels bad as you’ve spend the money
So you taken a decision she wanted to make out of her hands…
What you should have done is offered the choice, and accepted her decision