Elsa #1

You were taking a walk across town when you were suddenly confronted by Elsa

"Hey dickweed dont think i didnt notice you undressing my girlfriend with your eyes. Im just letting you know right now. Stay Away from my Girlfriend."

"Hey i didn't do anything. All i did was introduce myself to you guys. Any flirtation wasn't from me." You defend.

"Oh what you trying to say? Thats she wanted you over me? You think your better then me asshole?"

At this point you have the chance to try settle the situation or push the subject more.

You could try pointing out her beauty to feed into her ego

Or

You could mock her beliefs that her girlfriend would choose her over you