Samsung competes and partners with almost every major technology manufacturer out there; I would find it very odd that Apple would shift away from Samsung just because Samsung makes competing products.
Obviously you don't actually understand the relationship here.
They operate like most other major Korean or Japanese companies, in which backstabbing is part of the normal day, and they literally don't understand when American companies get angry at this. I've seen it in person many times over the years, where this blank expression and lack of understanding represents their entire side of a screw-over-job.
It was well known from the start that Samsung would inevitably decide to rip off the R&D done by Apple, by back-room assembling all of the same parts ordered by Apple. I'm surprised Apple has lasted this long in this business relationship, and it was probably out of necessity-only, for the last year or two, while they cultivated a new relationship.