Lol the denial is hilarious in last page.
I think it's less denial and more that Sanda is so socially inept and naive on some subjects that she has no idea what love feels like nor that what she just said is a common way of phrasing a love confession.
I think that Sanda is just saying what is on her mind without actually thinking about what she is saying. It seems like even if there were actual romantic feelings within her she is just too unaware of those feelings, causing any thoughts of "being together forever" or other romantic thoughts to pass her lips unfiltered by normal mental considerations of the implications such words suggest. I'd like to think that her feelings aren't strong enough for her to register them properly, but they are at least strong enough to influence her thoughts and her choice of words.
Simply put I think Sanda unknowingly wears both her heart and her mind on her sleeves, to the point where she probably says a lot of embarrassing or serious stuff non-nonchalantly without thinking.
Alternatively she could just be lonely at home, and due to the other woman's friendly nature and the amount of time they spend working together Sanda has grown attached to her. However, because of her nature Sanda didn't think her words through before she said them, making it seems like she was confessing and blowing the entire thing out of proportion.
I like the "subconscious romantic feelings" idea better though. :3