Can I begin by saying you've summed up everyone's comments here and added your own (and better) sense to it wonderfully? 👏 Has to be one of best comprehensives of yesterday's episode. I'm adding my remarks back to your observations below.
It's interesting that when she'd first entered and Kesar had turned upon her with the mujhe maaf karde Gulaal - it was my last moment of logic in the episode. Just that second I did think how could apologize like that, because it was putting the most crucial bedroom conversation to redundancy; and I did realize Gulaal had walked in not knowing for one second what she should expect - thereon, I suppose, even more than Kesar (while watching) I was sucked in by Gulaal's mahaan words 😆 No seriously, I think I'd been too deprived of Gulaal ever give Kesar even the mere can civilly co-exist status, and I just ceased to think this was going back to square one. Interestingly, like you say, Kesar's expressions do seem like he wasn't duped as fast as me - well he wasn't duped at all, he only chose to let it go, given his let Gulaal go move had been bigger than this. Anyway - at that point I was comprehending Kesar's not immediate flood of happiness at Gulaal forgiving him as being shallowed by his realization that Gulaal is expressing so much 'freedom' and 'happiness' in being freed from his shackles - and I thought that at least part of that irony had hit him bad. Even as he was ready to push all of 'himself' as secondary to Gulaal (who btw has been professed the epitome of sacrifice in this show) it did kill him - the fact that she should be so happy about their end. I still think a part of his expressions was that; but the majority factor has to be what you point out, his awareness of her relieved regression. He can see she's back to square one - what's worse, when she uses the word khushi, you can see he knows this time he wont be standing in the way of regression and her. [although, I like to think, at this point, that while his current plan may be to let Gulaal be, just so they can have this happy delusional state - he's going to snap eventually. Kesar may have been previously impulsive and immature - but he was never the one pulling off an ostrich act.] When he tells her this is all going to end in 3 months, her face clouds again, because her antenna has detected foreboding of Kesar the man mode - but more than her, noticing him is proof that he's very broken and resigned. It's not simply from letting her go - it's from accepting defeat to reforming her self destructive means. It's resigning from making her see light of the day - he's just tired. And when he tells her to be friends, and she looks indecisive, he adds itna to hum kar hi sakte hain It is every sense of a pun. As if of asking her if this doesn't invade her boundaries of 'purity' and become paap - being friends - like he's just indicating warily there there is no preach speech she can give against this... at least this! And you can see Gulaal gives in because because she can see there's no choice - but she comes around to spin off the friendship to a patronizing role anyway.
I think what really did go down well with me all through the episode - and still sits as a satisfied duck - is Kesar calling a spade a spade. He's given up on the aggression to make his point, but at no moment in the episode does he lie to her or himself, or anyone. When he's apologizing it's not to simply win back her good side and certainly not to offer her the half way grounds to make peace - but truly in repentance of his old unknowing tactics. When she accepts his apology and hand of friendship - he knows exactly what he's stepping into, but he does it because 'Gulaal's happiness is primary'. He realizes this is not the real happiness he wants to give her, but he's also come to realize this is the only way he can take a shot at its inception. When he tells Gulaal it maybe 3 months for him to get over being used to her, or more, or (never) - he's candid as hell. No doubt he can see the closing walls in her face - but he doesn't lie. He's stopped screaming his lungs off it - and he's not rubbing the 'love' in her face - but he's not masking himself as another person like she is either.
I thought the kitchen scene in the start was particularly double edged. She tells him that he must still believe that if MB is upset with them , it hasn't affected his love for them - and it's almost like she's speaking her mind - and even though she may not know or realize, Kesar does. When he asks her, hum mana lenge na... - It's almost in double meaning, like MB is not the only person he talks of. Interestingly, Gulaal's approach to MB's topic is exactly reflective of her nature - of how she truly does care for people in her life, but how innate it is within her, this sense of I can convince anyone to finally fall in line with me. In some ways she's like a young teen - who cannot comprehend or appreciate the fact that she can be wrong ... because she's always been taken as more mature of teens, and because conveniently within her own own head she has translated that to imply she is know it all and know it best and that no one understands everything like she does. Point being, Kesar knows exactly what he's doing and what he's letting happen. It is therein I rest my faith that he will snap to Gulaal's illusions at some critical point - perhaps he's then, gong to be the one to serve her the pointer, as Talli served him one. We've all surprised and shocked ourselves with Talli's genius, but thing is, she always did understand Gulaal on this front and could hence explain it to Kesar. However, to imagine she has become wise or smart - er, no. She still has no idea how Kesar's mind works - she is not one second closer to getting inside his head and that is what... sort of pokes my ease about TK in one frame.
Anyway - thanks for the comment Fivr - like I said, very well analyzed.