Actually, if both of your hands fit the same basic gun, there's a lot to be said for matching guns: ammo purchases become easier, holster/gear can be traded around, and if for any reason either of you needs to shoot the other's gun, you are not going to fumble around with an unfamiliar manual of arms.
Even with you as a lefty & her as a righty, it's not so bad to have an available "spare" holster that goes on your "wrong" side. If you sprain your wrist or break your trigger finger, it's very useful to be able to swap to the non-dominant side for the duration.
But if it bothers you that much, ummmm. It is not at all difficult to run a 1911 as a lefty. Get an ambi safety (you should on a carry gun anyway), use forefinger or middle finger for mag release, and your right thumb to lock the slide open. Drop the slide using overhand. Sounds awkward, but I've done it and have seen it done very quickly and well indeed. All a matter of practice.
Still, IMO it's better to stick with a gun you love. Don't bemoan matching guns -- just think of all the advantages!