I am certain now that they r having an affair. Facts:
1) Ipsita's expression when Shiv and gauri r talking abt love.
2) Ipsita depression and subsequent talk with Anupam.
3) Shiv expression when he agrees to talk to Ipsita on Anupams behalf
4) Shiv telling her why dont u say to him. and ipsita saying she does not love anupam.
5) the playful way shiv says that he only loves 1 girl & the potrait of the girl is on his wall.