I can't claim experience with your situation, but I see this --
"leaving our religion (which practices shunning) has left a huge void in our social life which she has been able to fill by reconnecting with past acquaintances"
-- as the first thing to resolve. If you're out there in the world, participating in groups, trying new activities, meeting people and making friends, you probably won't feel so left behind, you'll grow as a person which can only make you more attractive to potential partners, and you may well meet a friend who becomes something more or who introduces you to someone who will. Deal with your dearth of friends before you try to tackle your dearth of lovers
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.