Girls Gals

We understand that when we ask you out on a date, sometimes you're busy and can't give us an alternate time and day. Some of us will take that as a rejection.

When you're "turning us guys down politely" whe we ask you out on a date, how do we know when to take your reason at face value or not? (When are you "busy" or really busy)

There's this friend of mine who I like; I told her I like her, she tells me that "she is not interested to be in a relationship with anyone." but is willing to stay as friends with me
So I took that as her way of turning me down politely.

The next time we met we went to see a movie, after I dropped her at her home, she then offers me to give her a kiss. She was also flirty with me throught out that night.
Days later when she asked me for help, she then says "Thanks", so I said, "Hey it's not a big deal, you're my friend after all", she then says, "oh" as if she wants me to say I'll do anything for u.