Question: In our country, people when celebrating weddings, they do some special customs. I want to ask about a special custom. In the wedding night, after the groom enters with his bride alone in their room, somebody expect them to have a look to the under clothing of the bride in order to be sure that the bride is all right. If the groom refuses that, they gossip and they create stories about them without any reason. This wedding practice is it forbidden? And should the groom refuse this practice?

Answer:
Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

It is legally (from the Islamic perspective) prohibited for the husband and wife to divulge to others their bed affairs and marital details.
Imam Muslim in his Sahih narrated from Abu Sa'eed Al-Khudri (may Allah be pleased with him) that the Prophet (may Allah's peace and blessing be upon him) said: The most evil of men in the sight of Allah The Almighty on the Day of Resurrection, is the one who makes love to his wife then disclose her secret.

If this matter is verified, then it is among the most abominable things which are to be strictly avoided. No doubt that it is included in the aforementioned Hadith (Prophet's saying). It also involves following other Muslims' private affairs, meddling in their secrets, and breaking their privacy. Hence, the husband must reject and condemn this practice.
Allah knows best.