Is the marriage valid if the husband asked his wife, "Do you accept me as a husband?" and then repeated the question, whereupon she answered, "Of course" the first time, then "I'm thinking" the second time, and then he prompted her with the answer and she said it?

Your marriage is valid, and there is no need to doubt it or renew it, as that only increases obsessive thoughts (waswasa). Self-talk or phone conversations with the wife do not affect the validity of the contract as long as they do not include anything that would invalidate it. The wife's refusal to renew the contract does not affect the validity of the original contract, because divorce is in the hands of the man, as the Prophet, peace and blessings be upon him, said: "Indeed, divorce belongs to him who takes hold of the leg [i.e., the husband]."