What does this 我却为你万千感慨 mean? I do know the meaning of each word in the following sentence.
我却为你万千感慨 

But I still cannot understand the meaning of the whole sentence. Google translates it as.
I feel so emotional for you

I doubt about it. The hard part for me to understand this sentence is because of the present of 却.
So what does the above sentence mean?
Google's translation isn't off too much.
却 is an adverb which is used more or less like &quot;yet&quot;, &quot;however&quot; or &quot;and yet&quot; in English. I say &quot;and yet&quot; because I often see it used as a conjunction, in place of 反而.
For example:

这句话那么简单，却点燃了我 (= this sentence is so simple, and yet it set me on fire)

万千 means &quot;a myriad&quot;, also in English used figuratively to elegantly express a large quantity.
感慨 means something like &quot;full of sorrow&quot;. Mdgb says &quot;rueful&quot;. Zdic defines it as 心生感触而发出慨叹. Which essentially is a feeling of such sorrow that you can't withhold sighs and moans. Also, given the proposed synonyms (感叹, 慨叹) it seems it's used in a verbal position. It's seems used like a stative verb.
So if you put it all together:

我 (I) 却 (however, yet) 为你 (for you) 万千 (myriad) 感慨 (rueful, feeling sorrowful)

It roughly means the subject's feelings are many and nuanced, but all of them related to sorrow and sadness.
A fluent translation (somewhat poetical) might be something like:

And yet for you I let out a multitude of sighs

or, taking 万千 less literarily, so many feelings that the subject is overwhelmed.

And yet for you I'm overwhelmed by sorrow