I cannot really add much to the excellent answers so far. I would question the "inseam" numbers a little. I wonder if the o.p. knows that inseam for cycling purposes is different than for buying jeans. It should be somewhat longer. The conclusions in post
#4 jibe with mine but I don't think those bikes are going to be available for $200 even on CL. But that's quibbling. What I'd really like to suggest is that the o.p. and his partner think seriously about getting a tandem for their joint riding adventures. I'm serious! Mixed riding can be stressful for both parties. Trust me on this. Tandems can be rented to test the concept without financial risk. FWIW.
H