The-Dream's pretty close to the Carter's and he takes their relationship with them seriously. The great thing about that relationship is that Beyonce and Jay-Z appreciate Dream's relationship too.
Did you peep the Roc-A-Fella chain he wore? Upon further inspection, Charlamagne was able to read it's inscription and it was gifted to The-Dream from Bey + Jay. This only means that Dream must be ride or die for this duo and vice versa...
So, does this mean, he'll never work with Keyshia Cole?
Luckily, this question was asked and The-Dream simply said that Keyshia "would understand" why he would not be able to work with her.
Seems rather unnecessary. The Dream has enough of a reputation and skills where he doesn't need to be limited to working with certain artists based on something so petty.