It probably was guilt driving her decision to buy it for you. Even so, I think it would be appropriate to just say something like "you really shouldn't have bought me this, I thought we had an agreement" but then accept it.
Don't let it change your gifting plans.
M: A really long time. Crisis: 5 years. She's still worth it.
Life is never made unbearable by circumstances, but only by lack of meaning and purpose. -Viktor Frankl
