[Yosei]

I actually had some friends go through this situation. I was the middle man. Both of them were my friends, and they were best friends (I'll call them um...Apple and Orange. Apple being the guy, Orange being the girl).

Apple and Orange were best friends, ever since they were kids. Apple met a girl, Pear, and became close to her and started casually dating her. Orange ended her friendships with Apple and Pear and went emo and started harming herself. Apple got really stressed out over the situation because he felt obligated to be there for Orange, but he couldn't help his feelings for Pear. In the end, Apple ended up choosing Orange and dated her, and Orange had him cut all ties with Pear. After 2 years of dating, Orange joined the Navy, and two months into boot camp, met a new guy and dumped Apple.

Thats just an example of how the situation could go, but it depends on the girls personality.

Oranges personality is very... girl-ish. She's emotional, sensitive, stubborn, tries to be independent, shes protective, possessive, and holds grudges.

But my moral of that story is that you never know how things could go, but all that matters is the present, so follow your heart.

IMO:
If Jenny really cared about her friend who had met a girl that he really loved, and made him happy, she should be happy for him. If she has feelings for him, she should be honest, and should have made a move earlier. But now that she's missed the chance, all she should do is be a supportive friend and hope for the best. Sounds like she had a little spurt of jealousy and selfishness there. If she wants to be that way, then the guy should distant himself from her. If she really cares and wants some kind of relationship with him, she will come back and accept being his friend. Its not right for her to put such pain upon him.