I am sorry that you are going through pain right now and that your relationship has come to an end.
Try looking at it a different way; it might help.
Having someone make a decision for you is never going to make you feel happy about the relationship being over. Our mind naturally wants to fight against what we are being told. When I was 17, I had a two-year affair with a married woman. Endless times, she broke it off with me, saying that I needed something more than she could give me. Endless times, I argued "no, I don't, I need this!"
In the end, of course, she was right.
That's point one.
But also - think about what their motivation is for ending it. Stress, if they're more self-focused. Guilt if they're a kinder soul.
Even if your girlfriend was thinking of you, there would also be some level of selfishness, the same way there is with everyone on the planet. It wasn't working for *her*. You couldn't change that; you can't change that... and it might help you to understand things from her point of view.
There are many reasons for staying 'mono' whilst your partner dates. Perhaps you're picky. Perhaps you're shy. Perhaps you're not ready. Perhaps dealing with the jealousy side of the coin is enough of a struggle, without launching into "let's make my wife feel jealous too and really rock the boat". Perhaps you're not slutty and want something meaningful. Perhaps you're in no hurry. Perhaps you're not sure if you want to be poly.
If your ex girlfriend, his wife, had you, her husband and a LDR to balance, that's *her* decision. If she couldn't balance her time, meet everyone's needs, that's *her* cross to bear. Can't meet some of the needs of three people? Don't date three people. I don't think that's her husband's fault at all.
I can understand what you are saying, but I don't think it's the case that the primary is safe not to look for others, whilst the secondary gets dumped for it. I think it's more about how you may have portrayed yourself and/or how she may have perceived you.
I have a primary partner. I look for secondaries who are very independent by nature. I don't mind whether or not they have a partner, or are looking for a partner - as long as they do not expect me to fill the shoes of a 'primary girlfriend' figure. I do not have the time or the emotional capacity at the moment. I ended one relationship for the same reasons you were given by your ex girlfriend. The girl I dated was, in my opinion, very clingy, very needy, very co-dependent and very pushy. No matter how much I saw her, it was never enough. No matter what time I said I needed to leave, she wanted me to stay longer. No matter what my primary relationship guidelines were, she wanted to bend them. No matter how much she told me she was happy, I could see that she wasn't. But she was emotionally masochistic (by her own admission, later on).... she would never have ended it. When I was 17 and in love with the married woman, I would never have ended it. She had to end it with me, to do me a favour.
Try to practice forgiveness... if you can? She was learning. You were learning.
It's important for everyone to lay out their expectations and not to expect things to remain stationary. Things can change - one person can fall in love and the other can back way off. One person can start off wanting something casual, but end up craving more. It's also important to understand NRE. New Relationship Energy (that buzz we get from clicking with someone new) makes us want to spend lots of time with a new person. It can give secondary partners the wrong impression when, after a few months, reality kicks in and the married/partnered-up person realises... shit... I don't have time to be chatting online for 40 hours a week... I haven't tidied my house, walked my dogs, played with my child, had sex with my husband in a month.
It's your choice whether or not you choose to explore poly again
But I do think that either way, many of the rules relating to poly can be transferred to monogamy. And now you're better equipped to talk about your expectations.
The number one thing I would say is a benefit to take with you into any kind of relationship? Not simply a list of "this is what I expect"... but, instead... "this is what I expect right now and for the foreseeable future... but... my biggest expectation... is that we can feel safe and free to talk to each other, if and when our feelings change." To be honest, they often do.
me: open poly (31, female)
GF: (41, female) my long-distance, long-term partner
Earth: (35, female) newly dating
Hubby: (38, male) GF's husband
Garcon: (28, male) GF's boyfriend/submissive
“Peace comes from within. Do not seek it without." ~ Buddha