Is it necessary for a child to adopt an Islamic name upon entering Islam, or can their Western name be retained?

Firstly, your Muslim friend should not have a girlfriend. It is permissible for him to marry you if you are from the People of the Book (Christian or Jewish).

Secondly, it is not a condition for your son's name to be Islamic, but it must not be ugly or specific to non-believers, as names have an influence on those who bear them. It is preferable to choose a good name for him before his birth, so that he is not a target of mockery or astonishment.

Thirdly, you can choose good names from the book "Naming the Newborn" by Sheikh Bakr Abu Zayd.