I (34m) live with my partner (32f) have been together for 5 years and have been poly for 4 and a half of those years. We went travelling together and then came back and ended up buying a house together and getting a dog over lockdown when we were not really able to see other people as much. I'm not a fan of the term primary and secondary partners, but obviously our living circumstances kind of dictate that that is the case.

Since then I have had two long-term relationships with two other poly people, which both lasted around a year and ended on good terms with us deciding to be friends.

Over the last four months I have started seeing someone new (25f), a friend of a friend who lives nearby. We have a ridiculous amount in common...not just normal new relationship energy chemistry, but like very very specific and wide-ranging coincidences, similar interests, finishing each other's sentences, the exact same tastes and outlooks on pretty much everything...just an incredible amount of synergy that I have never experienced with another human being in my entire life. She is also incredibly beautiful and just an all round lovely human being - pretty much the ideal of what I would want in a "perfect partner". She is fairly new to polyamory and was in a relationship with one other person and casually seeing a couple of other friends off and on when we first started dating. However, her other partner has left to go travelling and now she is contemplating whether polyamory is for her.

Both partners, myself and a group of friends all recently went to a festival together and they got on really well and it all seemed to be very kitchen table polyamory positivity...but when we got back the girl I've been dating for the last few months has basically said that she found it very difficult and she is coming to the realisation that she is in love with me and is finding it hard to share me with someone else. It is especially hard for her as my partner and I live together and have a mortgage and a dog and our families know each other...etc. and now my new partner is worried that she will be second best or some sort of add on, because of the established life I have with my other partner. She doesn't want to be a secondary partner, basically.

I suggested we take a couple of weeks apart to reflect on things and then see how we feel, but my heart literally feels like its breaking and she is all I can think about - I honestly feel like a lovesick teenager. I don't want to jeopardise what I have with my partner that I live with, but at the same time I can't stop thinking about how much I love the other person and how what we have together is so rare - I've literally never met anyone who makes me feel like she does and I'm worried I'll never find anything like it again.

Any advice on how I should handle the situation? I don't want to jeopardise things with the partner I live with as she is so sweet and caring and reliable, but I am falling head over heels for my new partner who I have a crazy amount in common with.