My friend who is Shia got married with a Sunni girl. The father of the girl gave in writing that he is not responsible for the girl and she has all the rights to spend her life as per her wish and will (it was a love marriage).
After court marriage the boy took her to his house where again Nikah was performed as per Shia rules. After few months the couple felt that it was a wrong decision. One day the boy gave her tallaq (the boy said afterwards to the family that he was joking as there was no witness).
What is the concept of tallaq in Shia Islam once it is given as mentioned above?