Over the years I've car camped/ backpacked with a few lady friends and have tried both the double bag/ single mate-able bag approach.

The gals had one thing in common, they were always cold.  I was always too warm.  I'd leave my side unzipped, and as noted when I rolled over they got a cold shot of air.

I got an elbow in the ribs, usually accompanied by a few choice words :'(

I finally settled on an over-sized bag for me, that could accommodate two for a time, and they had a suitable sized bag for their sleeping needs. Everyone got a good nights sleep and my ribs never felt better ;D  Worked out better all the way around ;)

I used 2-25" wide Thermarest pads side by side and they provided a good nights sleep. Now there are better/lighter choices.