Incapable of flirting?

I know I'm going to get called a nerd for this, but online I'm good at flirting, I'm cool, I'm calm, I'm collected, I can talk to anyone easily... but face to face I'm a dork who can't keep track of his own words... this girl I've liked for a while and have been hanging out with without telling her how I felt, I finally told her. I thought I had everything I needed, I was mr. cool, I would convince her that we were made for one another so easily, but when the time finally came to tell her I stammered, I mumbled, I didn't know what to say, and then finally I just freaked out, apologized a couple times and walked away... why am I such a loser?
Incapable of flirting?
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