What is the ruling on preventing a wife from contacting her young male relatives, and is that considered a severing of kinship ties, and what is the ruling on her contacting any young male from the family?

A husband has the right, indeed, it is his duty, to prevent his wife from contacting someone who had wanted to marry her, due to the potential for fitna (strife/temptation) that could arise from such contact. And no severance of kinship ties results from the absence of such contact.