Why do I get jealous over a girl even though I don't want to be with her at all?

 To correct the sentence "I'm surprised he signed a contract with you when I told him his four-month deadline is not reasonable, and he showed no understanding or flexibility," you need to change the verb tense of the phrase "is not reasonable" to past tense. This is because the sentence is describing a past event. The corrected sentence is:

I'm surprised he signed a contract with you after I told him his four-month deadline was not reasonable, and he showed no understanding or flexibility.

You can also change the word "when" to "after" to make the sentence more grammatically correct. However, the original sentence is also grammatically correct.

Here is another alternative way to write the sentence:

I'm surprised he signed a contract with you after I warned him that his four-month deadline was not reasonable and he showed no signs of understanding or flexibility.

This version of the sentence is more specific and provides more information about the speaker's warning to the other person.

I hope this helps!