So I just reached lvl 5 with her and I told her that I would totally ask Kou what his type is, so she seems to like him but can I still date her when I reach lvl 10 even though I offered to ask? Also what would happen if I refused to ask?

Also please avoid spoilers here

You will end up dating her soon. I won't spoil anything that happens after that, but don't get too attached.

aaaaand you still spoiled it. Way to go with a typical "I wont spoil it but...I´ll totally spoil it anyway" answer.

If you refuse you get reverse relationship.

The next conversation you have with her will be the important one.  According to GameFAQs, you need to choose the second response for both of the options you'll get when ranking to level 6.  Should be a pause, then the nice response for the second question.  That sounds like the choices you want (without spoiling anything).

The Ai S.L. has some hillarious moments in it (especially from 5 to 6), cant wait till the ER will go for it. Ai (aka suicidal bitch) even tops drama girl.