perhaps it is just me, but i don't think your problem has anything to do with sex. from what i've read, it seems to be about trust. jane doesn't trust rich because he hurt her. it's great that he's apologized (assuming it is sincere) and that they want to work through it--but this is a big hurdle in any relationship.
that's not to say jane thinks rich is gonna cheat on her or anything along those lines--it just seems she doesn't trust him because she feels he judged her and hurt her feelings when she was honest with him. that makes any more "sharing" difficult--not just in terms of a nice sit-down-and-share-convo, but any opening up of herself to him emotionally, including in the bedroom.
rich says things have improved to the point where everything is fine unless there is an argument and then it all comes bubbling back up. well, that tends to happen when you have issues that aren't resovled.
but i don't recall jane mentioning that everything is great the majority of the time. and really, we aren't talking about rich's feelings anymore--we're talking about jane's.
jane says she loves him but isn't "in love" with him. having been there, done that myself i'm gonna go on what that means to me. if it doesn't ring true, perhaps you'll need to clarify what it means to you. you think rich is a good person and a worthy friend--as an individual, you love him. much like you love anyone else you feel close to in your life. but you aren't "in love" meaning, that bond you used to feel as his gf is no longer there. you don't feel connected to him in a way that makes your relationship meaninful to you. it isn't about that initial rush of mushy gushy love you get when you first hook-up with someone being gone, it's about the level of closeness you once felt not being there anymore. that sound about right?
imnsho, you can tackle this a couple of ways depending on your individual preference and circumstance. if things are good more than they are bad, you can take a chance and try to work it out. if not, you can cut your losses and move on. or, if you don't want to have to deal with these issues you can ride out your time limit and walk away--never getting the closure you might have gotten with your other options.
you guys are young, but you aren't that young. people your age get married all the time--hell, people your age are getting divorced all the time too! so really, what is this relationship worth to you? how much potential is there in it and how much effort are you willing to invest? a few months may seem like forever right now, but if this is someone you could see spending the rest of your life with--3 or 4 months is nothing. your relationship is still relatively new which is going to make your decision that much more difficult. there aren't a lot of good times to look back on and see you through the rough spots (compared to people who experience trust issues after spending years together).
i don't think anyone can tell you how to learn to trust someone again. but i do know that it starts with a choice and it takes a long time. how long is up to you. what you need from rich is also up to you. you want to understand the what and why of his emotions? best of luck girl, you can spend years with someone and never get past the tip of the iceberg. emotions are not always logical and for many people, expressing their emotions is difficult enough--explaining them to someone else is even worse. even rich may not be able to provide you with a clear reasoning. and even if he does, you have to be able to believe what he tells you.
counseling might help, but you're young and this isn't a long term relationship. counseling is a big investment (in terms of money, time, effort and emotions) so it may require more commitment than your relationship is worth to you. (and that is NOT a bad thing in these circumstances. you guys have only been together a few months, devoting just as much, if not more, time to counseling this early on is huge.)
sounds like you need to spend some serious time doing a bit of soul-searching. but whatever your decision about
this relationship, what you learn from it will help you in every relationship that comes after (romantic or otherwise). it's good to know what you base trust on and what it takes to earn that back. it's good to learn what your personal boundaries for trusting are and recognize when they have been crossed. as much as i know you hate going through this right now, there is the potential to learn a lot about yourself from it.