Is the fiancé's statement that wearing a long, loose garment would make people shun him and not accept him a valid one?

The Prophet (peace and blessings be upon him) preferred the qamis (a long shirt), but wearing it is not a religious obligation. If a man is in a country where its people do not wear theamis, there is no harm for him to wear the customary attire of his country, as long as that attire fulfills the requirements of Islamic dress.