Great suggestions, personal feelings aside, here, Mike. As somewhat of an expert on marriage (a total of 38 years, albeit to several different women), I feel able to contribute to your dilema abroad.
First, make sure even if you decide to tie the knot
or not, you both have a Power of Attorney over each others affairs with respect to finance (including disposal of assets: this is greatly helped by having your joint assets like cars, boats, houses, etc., secured in 'and/or' names such as John Jones and/or Mary Jones), also POA for medical
decisions, treatment, including end of life (when to pull the plug) and keep them with you when you travel.
Traveling in muslim countries is greatly helped by have the same name on your passports. I think it was wife #2 joined me on an overseas trip to Dubai before we were married and we had a rather difficult time staying in the same room. We finally managed it by meeting up in a restaurant, walking back to the hotel
and just heading upstairs. She told me it made her feel like a hooker!
I now have dual citizenship and depending on which country I'm travelling to will dictate which passport I use.
No problem is insurmountable as long as you plan for as many eventualities as you can.
Some sound legal
advice from an attorney who is familiar with the laws and customs
of the countries you plan to visit would be a good idea. Capt Phil