Can you replace 'whose' with 'that'? [closed]

I was browsing through reddit when I stumbled upon this sentence:

I’ve dated a few girls that English wasn’t their first language and it was always a struggle when things got really emotional.

I could only make sense of this sentence if I replaced that with whose.

Is it grammatically correct and would native speakers use this construction?

Solution 1:

In mathematical writing we often want a construction like this. You may see "such that" used in this situation: "... a few girls such that English wasn't their first language". (This is not common in everyday English, however.)

Mathematical example: "Does n have a factor k such that n/k is even?"