Am I doomed to always feel weird and uncomfortable with the idea of my partners seeking other partners?
It gets better. Stuff that helped me so far:
- All the poly books
- Books/podcasts on meditation and letting things go
- Self-help books on your particular childhood issues (everyone has them; I really needed "Adult Children of Alcoholics")
- Therapy, if you can afford at least a few visits
- Cultivating a rich life with other friends and hobbies
- Figuring out which ways you need your partner(s) to help you feel secure, and then asking for them
- Getting experience in all the relationship roles: incoming partner to an established relationship; loose-end arm to a succession of Vs; hinge; trying out having FWBs and other casual relationships
- Having some kind of "carrot" to keep you motivated toward growth; for me, the new boyfriend has proved to be my most effective one yet
- Posting here, both journaling and advice-request threads
- Time
Also, you might find your level of comfort varies from partner to partner based on history and individual characteristics of the person. Like, at this point I'm 100% comfortable with my husband doing pretty much whatever, but I bet I'm going to experience some (hopefully manageable) jealousy if/when my boyfriend starts dating someone, because it's newer and less solid, and he's not as poly-experienced, so it's sure to be a wilder ride. I have so many better coping and soothing strategies now, though, that I know that even if things go completely off the rails and I get my heart broken, I'll still be all right.