Praise be to Allah.
If the marriage contract has been completed according to the conditions of sharee’ah (see Question # 813), then it is valid and will remain valid as stated in its terms, unaffected by the passage of time. The fact that you have spent six months without consummating the marriage will not invalidate it as your friend is claiming without any knowledge – if indeed you have understood him correctly. In this case you should advise him to fear Allaah and not to try to issue fatwas without knowledge. If he had advised you to make sure that your wife travelled with a mahram it would have been better. We ask Allaah to give you strength, blessing and happiness in your marriage. May Allaah bless our Prophet Muhammad.