Neither Ranveer nor Ishani disrespect their friendship with Ritika and Shikhar respectively. In fact they feel obliged towards them hence the guilt. In the real world, they probably would have made compatible and practical couples (if Ri was still the good girl she once used to be). There would be no issues because they would be showered with love & support from their spouses.
With Ishveer it's not just a matter of love, it's a matter of being Ishani and Ranveer. They don't need love and affection from just anyone, they need it from each other. That's their 'problem'. So even if Ranveer thinks Ritika has been with him through thick and thin, even if Ishani thinks Shikhar unconditionally loves her...it cannot penetrate through because both Ishani and Ranveer have a sense of belonging to each other.
If they want to be loved, they desire it from the other. If they hate, they will only tolerate it for each other. It's not about needing love, it's about needing each other.
Some caps from today's episode :)
















