Search Results: betrayed by a friend

Background:

Alright, so I have a friend who was talking to me about this girl that was in his class (she use to be in one of our classes last year).

He (my friend) was all flustered and what not over her, and I could tell (by the way he kept talking about her) that he was developing somewhat of a crush on her.

So long story short, I highly recommended that he just talk to her already, and he try to get to know her instead of acting like he was trying to "bed her" (To his credit, he said he never had those intentions in the first place, but I had to make sure :S).

1 day later...

I'm walking out of a classroom full of about 140 pplz, and while slowly streaming out behind a sea of people, I catch a glimpse of the girl that me and my friend were talking about the other day. I hadn't seen her since the last day of our previous class, and I never knew that she was in my class now. Right then and there my initial thoughts were somewhere along the lines of "OMG, I think I kinda like her."

Now, to ease you all's Drama meters, I never actually got a chance to fully see if that was actually the girl at question, and I never pursued anything outside of my initial thoughts. But that leads me to my question for you all::

-------------------Question------------------

What should one do if they ever find themselves crossing the lines between a friend that someone has essentially confided their feelings in ->Too-> a competitor for the heart and mind of subject that they had once helped friend strategize over?

Sidenote

I'm pretty confident in myself enough to know that I would never attempt to betray the trust of a friend without their prior knowledge of the impending betrayal. It may sound strange, but I'd much rather stab someone in the chest than stab them in the back.

Also, the girl at question is more or less another pretty face that I have seen a hundred times on already. All that goes to say that I always have other options that would avoid betrayal if I were really that intrigued in pretty faces :P