[aki]

Hello.
Nice to have a chance to ask English questions.

Now,I got a question from the English reading test that I took the other day.
That was about a chinese man who loves american woman.
One day,he tried to tell her that he loves her and wants her to be his girlfriend.
He said in broken English;
"You are a girl I love.You are a girl I'd like to have as my girlfriend."
But she stared at him coldly and walked away...
Many years later,He noticed the mistake that he said"a girl"in stead of"the girl".

I'm just wondering why she got angry to be said "a girl"...
Does it sound strange to native English speakers??

I'm looking forward your answer.

Aki