Im a Cheater magnet

Certain kinds of people attract certain kinds of people, often is the case with BPD girls and Co-dependant guys, and vice versa. It's the worst mix. It's true that softer and kinder people get taken advantage of because you're drawn towards people you can comfort. There are definitely healthy relationships you can get into where you're the comforter, it's all about mutual respect and often times the more intense and passionate ("i can't live without you") sentiments are the dangerous ones. Good luck, I know what type I attract so it's good to be aware of it! You'll find someone who isn't a succubus.

I'll admit I didn't read through all the replies people have already lain out so I may be repeating what has already been said. Date a different type of girl; don't be the crying shoulder, guy-friend-that-gets-vented-to from the get go; you're not being seen as an equal when you put yourself in that position and it makes you much more likely to get cheated on, especially if you're not around due to work. If I've learned anything from my own mistakes, it's that most relationships fail simply due to a lack of communication--the fear of saying what you really feel and getting a negative response from the one you care about. This, and ignoring red flags. Don't ignore red flags just because a person has other good attributes--even the worst people have something good about them. Nobody is perfect, and minor flaws are negligible, but never dismiss big issues. Women and men think differently, and that's completely ok. Many people hate to admit this, but if they had, it's very possible their relationships would have gone a different direction. Instead, they end up bitter towards the other sex, entering a grass-is-greener, "men are this", "woman are that" type of mindset. It's easy to get around this difference-in-thinking issue so long as you're actually honest with one another when you bring up concerns to the other party, and when things go wrong you think about what you did incorrectly rather than only focusing on how you were wronged (conversely, blaming only yourself isn't constructive either). If you grow bitter at how you were wronged, you'll never evolve as a person from one relationship to the next, and you'll treat your new partners with leftover animosity from the previous. If either person doesn't do their part you end up in a game of mental gymnastics, and eventually (not necessarily due to cheating) your relationship is going to fail. Again, date a girl different in personality from the previous ones, and under different circumstances.

Early 20s is where people are still "finding themselves." Also, assuming you're from the States. TDY over seas and date someone from another country. As a whole, Americans are preeeeeeeeetty broken when it comes to dating. Also, pro tip from a former military gal: Don't let anyone know you're military when looking for someone, you're gonna find SO many people trying to catch a free ride.

So you are seeking a monogamous relationship with someone who will be faithful to that contract. First off, when you got with these girls did you actually present that as a requirement? Or did you just assume "Oh we made banana sauce together and now we are a thing"? Secondly don't be an emotional tampon, tampons get gross and are only meant to be used once. Someone mentioned mental illness before that is a good point, more so than that though.... A person with low self image is more likely to cheat, you need confidence in yourself and any woman that you desire to be with should also have confidence, not be attention seekers, or have "daddy" issues Make sure that any requirements you have for your relationship are known, don't have any "Assumed Contracts" (what I mean is don't assume you are on the same page, determine-clarify-modify. I could go on and on about this but whatever you get the point I guess one last piece of advice would be to go about it as detached as possible, I let my partner know "You can go out and bang some other dude, sure... but I will lose all interest in you" that may not be your style but the way I look at it, I DO NOT OWN MY PARTNERS BODY and have know right to assume that I have exclusive access, but I have a right to my own, and if she is getting down with someone else I have a right to stop relating or modify the relating