Is what is happening between the questioner and her paternal aunts' daughters, in terms of coldness and lack of support, despite the kinship, considered severing ties of kinship?

As long as you maintain ties with them by visiting from time to time, you are not severing kinship. Perhaps an action or word from you offended your female cousins. Our advice to you is to increase your visits to them, to speak gently to them, offer them gifts, and strive to treat them kindly. By doing so, alienation and hatred will vanish, and affection and love will prevail, in fulfillment of the Almighty’s words: (Repel [evil] with that which is better, and thereupon the one whom between you and him is enmity will become as though he was a devoted friend.)