There are chances, hotel management is some time be very conservative and can spoil your mood by canceling your booking or force you to book another single room. To save you from the issue please always carry Id proof of both the partners. Please check with hotel management while booking room.
To help these are few hotels if you are unmarried couple from India will accommodate you in jaipur :-
Hotel Clarks Amer
Red Fox hotel
Hotel Vaishnavi bani park
Hotel metro view Station area/Sindhi camp
Please carry valid ID proof of both the partners.
Please note : Unmarried couples from other countries have no issue with most of the hotels in Jaipur . Still it is advisable to check with hotel management before you book the hotel.