JLPT question - what does のには mean in this sentence/

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    母親は嫌な顔ひとつしなかったが、娘の食生活がどんどん変になっていく　_______　困っていた。
    
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And answers are:

[code]

    のには 
     のから 
     のでは 
     のとは
    
[/code]

The correct one is のには, but I don't understand why.




the の of のには in this sentence is attached to なっていく to form なっていくの which is
equivalent to なっていく **こと** the に means "by" and the は is a topic marker, and
together they refer back to なっていくの and means that this is what is causing her
to have become 困っていた。

Hahaoya wa iyana kao hitotsu shinakatta ga, musume no shokuseikatsu ga dondon
hen ni **natteikuno** ni wa komatteita.

A Japanese native will probably come along in a bit and give more detail, but
I hope my explanation is understandable.




the の of のには in this sentence is attached to なっていく to form なっていくの which is
equivalent to なっていく **こと** the に means "by" and the は is a topic marker, and
together they refer back to なっていくの and means that this is what is causing her
to have become 困っていた。

Hahaoya wa iyana kao hitotsu shinakatta ga, musume no shokuseikatsu ga dondon
hen ni **natteikuno** ni wa komatteita.

A Japanese native will probably come along in a bit and give more detail, but
I hope my explanation is understandable.

