When Angela said that sex is a thing that people have, like a rottweiller, I thought of similar statements made on the show: "People always say you should be yourself, like yourself is this definite thing, like a toaster" and "Like romance is this thing you misplace, like an earring."
Anyway, I agree that Angela is afraid to have sex with Jordan. Why? A million reasons. I think one of the big reasons is that her parents have taught her traditional values, meaning not to sleep around and that sex IS a big deal. Despite her mini-rebellions, she still conforms to a lot of things they have taught her, whether it's because she truly believes in the principles they have taught her about or because she's afraid to make them mad or because she just hasn't given these ideas enough thought to decide if she agrees or disagrees.
She is also afraid because she is still a virgin. Sex is great, don't get me wrong, but losing your virginity is a one-time deal and while many guys are usually in a rush to lose their virginity to anyone willing to let them put their thing inside a thing, girls tend to be more cautious. Maybe it's a sick and unrealistic thing, but most girls want their first time to be special and with someone they love so that they can look back and remember it without thinking, "I can't believe I let that a$$hole have sex with me." So the big question for many girls is "Is this the right guy? Do I love him? Will he make it special?" Once you lose your virginity, you can certainly keep on having sex but you can never re-do the first time. As stupid and obvious as that sounds, it's true and something that girls think about.
Another fear is physical pain. Girls are afraid that it will hurt (which is often the case, sometimes due to the absolute ineptitude of the guys they have sex with because come on, how many 15 year old guys are good at foreplay? They watch scrambled porn and think that grabbing a girl's breast will make her writhe with pleasure). And when the girl is in the moment (okay, making out with some guy) and then she realizes where it's going and starts worrying that he will pressure her to have sex, she will be too stressed to relax and enjoy what is actually happening (the making out) which means she won't be aroused enough to want to lose her virginity. It's a vicious cycle.
Even stronger than fear of physical pain is the emotional vulnerability. Like fnordboy pointed out, society rewards males for having sex and stigmatizes females who have sex, especially in high school when kids have still retained much of the parental preprogramming. It's done in secret, the girl's parents would be upset if they knew (as evidenced by Patty when she believed Angela was having sex with Jordan), and people look down on high school girls who have sex. On top of the risk that people will write notes about her in class

Angela is concerned with being emotionally hurt by Jordan. Because society tells us that good girls don't have sex, girls end up rationalizing having sex - either "he loves me" (Sharon) or "I don't care what you think" (Rayanne). Since Angela still cares what people think, she wants to believe that Jordan loves her (or at the very least really likes her) before she agrees to have sex with him so that in the event that it DOES hurt and people do call her a slut, at least she will be able to justify why she did it.
Angela and Jordan are at odds here. Communicating his feelings is what makes Jordan vulnerable. Having sex is what makes Angela vulnerable. I think that the reason why Angela ultimately decided not to have sex with Jordan is that she wasn't ready. She knew that having sex with him would bring about even higher expectations for their relationship and it was already pulling teeth to get him to be seen in public with her. He wasn't willing to give her all the things she needed to feel secure in their relationship. She wanted him to be a regular boyfriend like Kyle, but he wasn't able to yet. I'm not saying that Jordan was using her for sex. I think that he did really like her, but he didn't know how to be a boyfriend and have a relationship because it seems unlikely that he had done that before. His experience (I assume) was hooking up with girls at parties or abandoned houses. Because of his inexperience as a boyfriend, Angela's expectations seemed demanding and "abnormal."
Angela didn't want to be just another person that Jordan ummmed. She wanted to feel special and she wanted Jordan to be able to make her feel that way in private AND in public. She wanted more from the relationship than sex - she wanted Jordan to be the kind of boyfriend who takes her to the movies and hangs out with her at school, not someone who hides her from his friends. Although we all know about the end of Self Esteem, we don't see a continuation of their outed relationship in Pressure. The closest we get is Angela driving Jordan's car in the parking lot. In Jordan's eyes, this is a big step but what does it mean to Angela? Is the the same as walking to English class together? Hanging out at lunch? Being walked to class? In her eyes, the relationship hasn't progressed beyond the Buffalo Tom moment in the hallway.
I think I'm beginning to talk in circles, so I will stop for now.
