My thoughts....

For backpacking I would not even try to do the couples thing for sleeping.  Separate mats and sleeping bags will be far more comfortable for actual sleeping if only that she will almost certainly want a warmer pad and sleeping bag/pad combination.  If you both used quilts or bags that fully unzip then you can adjust around for lounging...which you may need to do in Olympic NP since I hear it rains a lot there.  Some straps to attach the pads together might be good for that situation.

For a couples backpacking tent the BA Copper Spur UL3 is the gold standard to compare other options to.  Two doors/ vestibules is the main requirement.