Yeah this is what I got too. In short, as hurtful as it may be, you're a rebound of sorts. I am sure that you two do make a wonderful couple, and under different circumstances, I bet she would have been in love with you. However, I think she is still in love with the ENTJ. She never gave up hope that they would be together once he came back.Echoing what everyone else mentioned, it sounds like she's using you as an emotional crutch and buffer in order to deal with said ENTJ leaving (which I can imagine would have hurt big time; especially if you consider that she was in love with the dude, while he just up & leaves because he wants to "keep his options open").
As for you, you need to let her be. Be her support but don't do everything for and with her. She's not a baby. Love is beautiful, but a love where one person is always giving and the other constantly taking is toxic.
I'ma give it to you straight man. You're in the middle of an ENTP mind-screw chess game. It's like "checkmate, but I'ma let the clock run a little before I make it official, because I have nothing else to do until my next opponent finishes his game". It's an ENTP trap/game. Be nice .. have fun while it lasts. If it pans out then AWESOME, you beat the odds. I wouldn't set any type of expectations though.You just validated my entire approach. Thank you.
Okay well while I'm telling secrets and being straight lemme tell you that if I were her and this was the game I was playing I'd make you think that it was your idea for us not to be together so that you were the one who broke up with me .... I'd also beat you to the punch telling "other guy" about us, so that I could do it on my terms ... and so that I could solidify and manipulate his reactions according to my will.That would be very unfortunate for her. I have been stockpiling some photos, videos, and witnesses because I considered that I might need an exit strategy. These would certainly cause Other Guy to never talk to her again, seeing as he has no idea about us and I certainly know how to frame this whole thing for maximum effect, as I know him, his insecurities, and weaknesses very well. If she puts me in a position where I have no reason to talk to her again by ditching me completely, then I'd have no reason not to share them with him. I'm being very patient and understanding with her, and willing to accept that she has a boy toy if that's what she needs in order to also meet my needs and let me have my toys. If she's playing me in some sort of emotional chess game, she's on the path to getting schooled. I always cover my moves before I make them, and I suffer from that Enneagram 8 need to burn everything to the ground rather than let someone else have it. Then again, my kindness, patience, and tolerance are often mistaken for weakness.
Also, you didn't sound like a dick. Straight talk is preferable.