Now would you expect Ford to continue to buy tires from Firestone?
Samsung is Apple's biggest competitor in the phone space but Apple still buys a large number of the parts used in their phones from them. Apple has been steadily replacing things like processors with their own designs but this certainly isn't because of some petty offense they've taken to Samsung entering their market. It's because it's in their best interest to design their own parts (especially long term). Apple does come off as being emotional about Android with the decisions they've made (especially Maps) but implementing their own Maps and other features of their phones themselves is a good long term business plan. In the case of Maps, they launched too soon but working on their own mapping solution was a good decision.
Both parties are acting in what they believe to be their best interests. I don't fault either. (and btw I completely agree with your second paragraph)