Before coming to the question will talk about V’s feelings being hurt with Sai’s indifference.
I was never always a Sai supporter. She is flawed and she too had her lows. I didn’t watch the anniversary episodes. Just like I skipped the last two episodes. At that point I really felt for V’s character. He actually had put in too much effort. It was not in his character to confess his feelings so openly. He is shy and somewhere apprehensive of dejection. Sai may have had her reasons to not see his love and conclude it for care or obligation, but how she treated him was absolutely wrong. So I kind of liked the sadist, aloof V. I liked the sequence where he broke all ties with her before returning home. It was his hurt at her words, disregard of his feelings and attempts. But then he went overboard with his whole rudeness. He is either too gentle or too rude and harsh and he does tend to get carried away on each of these tangents. Unlike Sai who forgives and forgets and moves on. She doesn’t hold grudges. V does. Again both have their shortcomings. And both are responsible for where they are today. So if we ignore all V’s mistakes and inability to act or think in a more clear and intelligent manner, and overlook all the external elements, for an outsider, we would sympathise with V. Yes he has gone through a lot, suffered a lot and his yearning for Sai’s love, her rejections, his desperation to stay close to her, be with her in any capacity would have been painful. But that’s where we see another difference. V wears his emotions on his sleeves. So we felt for him at that stage. But Sai has gone through a lot as well. Just because she didn’t break down or show her pain so evidently it takes more to see her side. And that’s probably the reason we saw V’s pain first and then moved on to Sai. Because initially she was this outspoken, impulsive girl who could loud and rude. No one saw the broken she was inside nor did she show it. I loved the scene where she was talking to her Aaba breaking down (just before her realisation of love in that white suit). We haven’t seen such scenes earlier.
Coming to your question. Taking a step back. Why was Sai holding back till now? Or was she holding back? I feel she was. Her territory was clearly defined with the clause of the marriage. Being the fiercely determined girl she is, Sai always maintained her side of the deal. So she never allowed herself to think about that possibility. She denied it to herself unaware of the fact that these things are not under one’s control. So while she thinks that she never gave this possibility a thought, she was sub consciously holding herself back from it, guarding her heart. This comes from the fact that though she seeks out love and family, she is an independent unit who knows she needs to fend and look after herself on her own. And that’s precisely how she functions. Alone. So to your question, she isn’t sure. She is hoping for it. She has somewhere revisited those places in her memories which make it seem like a possibility. This started with the MiMo track ending. All she is currently focused on is that she loves him, and she wants to win him back. Her realisation has made her take that risk or rather not ponder on that fact at this point (with the current state of situation adding to it). She is high on love.