I ended up going with this zero degree sleeping bag. I suspect the coldest weather I'll be sleeping in is about 25°. https://www.amazon.com/dp/B00Z77AMOA/ref=cm_sw_r_cp_apa_i_XxiMFb8WCHDME

See the best sleeping bags for couples -

https://whynotreviews.com/best-zip-together-sleeping-bags-for-couples/

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https://www.amazon.com/TETON-Sports-Lightweight-Backpacking-Compression/dp/B00Z77AMOA/ref=redir_mobile_desktop?ie=UTF8&aaxitk=6HKz6oyqg9bdAg7YRkP15g&hsa_cr_id=3593999480601&ref_=sb_s_sparkle