thanks for getting it, jo
<3
disclaimer: the following is just my opinion on jealousy from my own personal experience, and how i choose to live my life. not judging anyone else's feelings on this matter.
i think for me there's also an element of - my being polyamorous, to me at least means that i have certain feelings/opinions about jealousy, etc.
one of those feelings/opinions is that - if an ex and a friend dating is bittersweet for me or makes me feel jealous or upset - that feeling jealous or upset is MY problem. not theirs. same goes with a current partner dating someone else. i don't see it as my personal right to say that they should not be happy together because it makes me upset.
obviously there's an element of discretion involved - if we just went through a bad breakup a month ago, don't be an asshat and date my ex and rub it in my face. and ask me first or break it to me gently.
but part of why i don't consider it a right to deny my friends and exes the possibility of dating is because - if it makes me feel shitty, that's because -i- have issues i need to work on. (i mean, unless there are other issues going on, like the ex and the friend shouldn't be together because one of them is a terrible human being, or something.)