Well, this isn't your mother tongue after all; I wouldn't be surprised if anyone had difficulty learning a language outside of their own.
Hell, I've had mandatory Spanish & German classes when I was in middle school. I was like, "So... why am I being forced to learn this?"
Needless to say, it didn't end well, which led me to believe that foreign languages don't mix with me. Thus, I'm completely mono-lingual.