Re: got ex back, left again... confused and discouraged
If this girl is the world to you show it. Don't say it. Same rules of the game apply as they always do when you are playing attraction.
What you are dealing with is insecurities within yourself as much as she is dealing with the insecurity that you will cheat or leave her. I'd suggest you hold a frame that showcases your interest and doesnt stray from her as your only interest. The best way to do this is to accept the good, the bad and the ugly as it comes. Since you believe you're still in the dog house thinking she has all the power i believe you need to lead in the relationship. Even though you made a mistake in the relationship it doesnt mean you have to bow down to every word. I believe it means that you have the oppurtunity to build a greater relationahip now than ever before because you have failed.
Consider leading in which you're giving her prime examples that you've chosen her. The idea of preselection is still there in her head but the idea of commitment isnt so much. Some better ways to prove this is through preloading and qualification on top of reframing your intentions that she is your focus. Don't bring up topics that questions the relationship. Doing so is similar to asking a girl if its ok to kiss her. It loses the momentum that you're building in tension. Instead always create and generate situations in which she's filled will too many emotions to hold back a smile or laugher.
Since she's brought up other guys or maybe might be trying to get you to feel jealous i believe the best thing to do is to ignore it or reframe it in your head as if she's talking about girls she's hangjng out with. Jealousy is good and bad. Its good so you can gauge the emotional range in the relationship. Its bad to act upon it. My suggestion as to what to do from here is to go along with her idea or intentions. If there is room for you to part take--just turn things up. If she says theres going to be drinking and people--lead the group and turn it into a drinking game and when its over isolate. If theres people, drinking and music turn it into a dance party and when its done isolate. If its a concert with drinks and other people then party then isolate. The goal here is to lead everything so you are having fun and shes apart of it. Let her try to play games its ok, but when you go in knowing it might be turn things around into your favor.
As for insecurities you need to re-examine your goals and approach. Don't make it about not losing her--make it about preselection and how you have chosen her. Never fail to lead even though you've made a mistake.
Every moment counts, get out of your head and enjoy it.