Hey Trisha, I checked with my friends who are lawyers and they say that according to the law, hotels do have a right to reserve admission on any ground, except caste. This means they can discriminate based on their personal moral code, however outdated it may be.
Hi Trisha, Indian law doesn't prohibit hotels, restaurants and clubs from having their own rules. Thus, hotels have the "Right to Refuse Service" as long as they are not violating Article 15 of the Constitution of India which states: "(2) No citizen shall, on grounds only of religion, race, caste, sex, place of birth or any of them, be subject to any disability, liability, restriction or condition with regard to (a) access to shops, public restaurants, hotels and places of" A couple's marital status doesn't fall within the grounds mentioned in Article 15. Therefore, YES hotels are within their legal right to deny entry to unmarried couples, however strange may that sound.