Hello there, do you think it's you that's reading too much into it? I mean it happens alot where the lady is really nice, etc and the guy reads that as the lady being into them but when really it's the lady being nice and caring.
Also you seem to have feelings for her and perhaps you want something to happen between you two?
I think it's either she genuinely see's you as a best friend or she may be worried about getting into a relationship with you because of what it would do to the friendship but she has feelings for you as well?
I had a friend who said I love you but she meant in a sisterly/friendship way, so don't read into that when she says she loves you because it's in a friendship way

Also this is not directed at you but at society in general, why do we have this weird perception that friendship is a level below a romantic relationship? In my eyes there equal, just like the relationship you have with your siblings, family, friends, etc
So yes to me absolutely guys and girls can be friends, etc otherwise incest would be on the rampage as well as other things.