When it comes to a flings and relationships, I am your typical no bullshit type of guy. If a girl does not want to hangout with me, or isn't escalating with me then I just leave and find another chick. Furthermore, I am upfront about the fact that I have other options in women, I do not rub it in the girl's face but it is clear.

answers to any of the numbered questions, especially 3 are really appreciated. Jealousy is never something I really understood since I have never been the jealous type.

Broadly speaking:
1. Is creating jealously in a girl really beneficial, or just childish and considered trying to hard. (basically flirting with and talking about and to other girls in her presence with the purpose of making her jealous and frustrated)
2. Why do girls try to make guys jealous? (I've heard conflicting views. Either to test the guy to see whether he cares enough about her to chase her, since she is afraid she does not really care for her, or to test him to make sure he is not desperate or clingy. Unfortunately, based on the two views chasing can be good or bad)

Specifically speaking:
3. A friend of mine a few years younger than me from back home has just started up college. Her and I are attending the same university. She has introduced me to a few of her newly made friends. My friend told me that shortly after introducing me to her friends that one of her friends finds me attractive and wants to hookup with me. So they decide to come over the next day. Before the girls head over I tell her to wait a few hours because I a meeting someone and wont be home. To which my friend replies, "are you going out to have sex with another girl, because my friend will fuck you instead." I tell my friend that is none of her business, and that they can come over when I get home. So the girls come over, and we have a good time. The 2nd half of the night I focus on escalating physically with the girl that apparently wants to fuck me. The night comes to and end, and I have the girl isolated on the bed, while my friend is talking to another guy. At this point, my target freezes me out so I get up and leave. I am partying with my friend and my target a few days later, the same thing starts to happen. I being to escalate physically, my target goes along with it, and then freezes me out. After she freezes me out she starts talking to another guy to make me jealous, so I decided to go to the after party without bringing my target or my friend. Long story short, I get that this girl likes me, she shows good body language signals, and we talk/flirt around a lot. Additionally, I am the clear alpha male with access to parties and resources.

My analysis of the situation is that girl likes me, but is nervous to fuck me now because she thinks I am hooking up with a lot of women. She is afraid to get hurt or used, and that's why she is playing games with me. I really need help on this one because I am hanging out with my friend and my target tonight.