I have been thinking about this more and more, from experiencing our open/poly relationship, reading my Osho book, and from (strangely enough) dancing.
I don't know a whole lot of the psychology behind these mindsets/frameworks/ways of approaching life. But I know my own personal experience with putting myself into each mindset.
I grew up hearing from my mom that I should never worry about money, because there would always be enough. (This wasn't the greatest message, on a practical level. The plenty mindset was great, but the lack of financial skills she and my dad taught to me was not). I have had to say a message like this to myself since I started dancing, because the money is so up-and-down; it's kind of like gambling (will I make a ton of money today? will it be a really shitty day, money wise? I am elated when I rake it in, and have slight feelings of depression and anxiety over feeling financially insecure when I don't). And really, the money has totally evened out over the long-term, and I have provided well for myself since I started. Having this frame of reference to apply to other places in my life is also pretty awesome.
When I am feeling emotionally whole, safe, and healthy it is pretty darn easy for me to remember and believe and truly have faith in the idea that love in unconditional and that there will always be enough love. I know that I hold this idea deeply within myself; during a Reiki session a while ago, that is precisely the message I heard from my spirit animals: I will always be loved. When I am feeling fearful or insecure, it can be so much more difficult to stay within the plenty mindset. Instead, my freaked-out little right brain screams at me: There's not enough!! Get all that you can! Compete, compete, compete!
The consequences of the scarcity mindset for me, especially related to the idea of love, is that I end up clamping down on my primary relationship with J. I get scared he won't have enough love for me, and that I will be found to be not valuable enough to deserve love. (Yes, this is related to earlier conditioning I received that love is conditional.) The consequences of my clamping down and shutting down to other relationships are that J ends up feeling less loving toward me because he has a more difficult time getting what he needs. It takes a lot of work on his end to provide me the reassurance I need when I am in a scared space, and everyone has a capacity for doing that kind of emotional work. Most of the time, he does a wonderful job. I become like a turtle when I am scared, completely retreated into my shell. When he can provide me with reassurance, compassion, and gentle reminders, I feel myself slowly coming back out and slowly moving back into the plenty mindset. It's an art, and one that we are becoming better and better at practicing.
I think another component of all this for me is the fact that moving into a plenty mindset simultaneously feels freeing and extremely vulnerable for me. It means leaving my heart open to both pain and pleasure, keeping my guard down to allow other love in my life but also keeping my guard down to feeling rejection, dishonesty, and other crummy relationship experiences. The painful experiences have a tendency to make me retreat, and I feel love is again scarce. The pleasurable and loving experiences make me reach out and I feel love is again plenty. The trick I am learning, is keeping myself within the plenty mindset as much as possible so that the emotional consequences of the scarcity mindset do not enter my psyche or our relationship as often.