Last 2 pages ruined all the wholesome vibes the manga had. SMH, I hope it's some bait and not really a big deal.
This story could still be wholesome even after those last 2 pages.
It really sounds more like Yuki's father (or other family member) was in some sort of financial trouble and used an engagement between our MC and Yuki to help with whatever financial issue they had.
Yuki probably just gave up because she felt she had absolutely no choice in the matter. Also probably didn't plan to love the guy she was being "sold" to. Then comes our MC and he treats her extremely well and she becomes what we saw in most of his flashbacks but this one.
Those last 2 pages do not make this non-wholesome...yet. Gotta know the whole story before we make that determination.
Having said that, it does seem like the light in her eyes is just gone and she has no life left in her and that really is just sad.