<human>: Can you succinctly summarize the text in 1-3 sentences?

Brief back story. I've recently moved to the USA from Australia, and met a girl who I've been getting on brilliantly with. Now we have been out for 3 months, said the L word, and she has moved to a city about one hour flight away. I have enjoyed the place so much I want to stay, so am seeking permanent residency. Unfortunately where I am requires me to get paperwork sorted out so I won't be able to move where I am from until April. We are both cool with this and I come up every 2 weeks to see her. We happily go out to restaurants and love doing stuff together. 

However, she has been a bit distant from me in the last couple of a days and has now come out and said that I am too nice. She said that when I first met her I was extremely confident and for example the day after I met her I told her to have a shower with me. She told me that this isn't something she'd usually do but because of how I was she did it. She basically said I need to be more like that.

I think when I get in a relationship I try to be the good boyfriend who is caring and looks after her, but now I am getting the impression she wants me to get a meanstreak in me. 

My question is, what honestly does this mean when she says I'm too nice, and where is the line between not being too nice, and being a total asshole to scare her off? 
Also please don't suggest TheRedPill. That subreddit doesn't promote a healthy relationship syntax.
<bot>: Girlfriend has said I am too nice, how do I get the balance right between not being too nice and being an asshole?