Sahir has built a wall around himself since Zeenat's accident. I'm sure 7 years ago it was heart breaking for him considering how the flashbacks are showing him completely in love with Zeenat. Sahir didn't give off the vibe of feeling guilty for gifting the car, I think just the loss of Zeenat, her being trapped in a vegetative state, not fully alive and not quite dead, is very big thing for anyone to handle and Sahir is dealing with it the only way he knows how and that was by self-preservation. He mentioned his reasoning for keeping the matter hidden to Kurti Appa yesterday, he didn't want people talking/gossiping about his personal life because it caused him pain. Also in the dream sequence with Aarzoo he told her clearly that he didn't want to her to be his ahdat, because he has felt that loss with Zeenat and doesn't think he can go through that again. His burnt toast and bitter coffee, a reminder to stop himself from hoping, preventing him from relying on things that may not last.
Also he is the head of a company and has people relying on him to make it succeed and if the employees and other businesses thought he couldn't handle the company due to his wife and her condition or somehow use that information to hurt him, his business would also suffer. How many CEOs and big corporations hide their medical/personal problems as they don't want the image of the company to seem weak. When someone is chronically sick or have a close family member that is a lot of people feel it to be a very personal and private thing and they don't want to be under the scrutiny of strangers.
