I'll try to answer as many questions as possible here b/c we really need an FAQ sticky for couples.
What is the couples match?
The couples match is simply a term used when they link 2 people rank lists. Thats it. It gives you some control over a process that is otherwise tough to control. The computers simply take your rank and your partner's rank and if you both match at that rank then you match. If one of you doesn't match then neither of you matches. Notice how I used the term rank and not program. I used that for a reason b/c the computer doesn't know the difference between programs. If your #1 rank was UCSF and your partner's #1 rank was NYU and you both matched at those programs that would be viable match. The computer doesn't know the difference between NY and Cali or any other programs you apply to. All it knows is did you match and did you not match? The bottom line however is that the only way one of you matches is if you both match. If one of you doesn't match, neither matches
The rank list: Depending on how important it is to be together will determine how long a rank list you make. Lets say for example that Bob gets interviews at 10 programs and Anna gets interviews at 10 also. Let's say that 8 of these interviews are at the same place but 2 aren't. There are many ways they can set up a rank list.
1) Only rank programs where they both got interviews - in this case their list is 8 long
2) Only list programs within the same geographic area - lets say Bob and Anna both got interviews to NYU and Columbia. If they agree that this is an acceptable distance for them to be apart, they can rank the different combos. This will add 2 ranks for every 2 programs you do this for. This would be in addition to the 8 programs they common interviews to.
I.E. 1) Bob and Anna both match NYU 2) Bob and Anna both match columbia 3) Bob matches NYU anna matches columbia 4) Anna Matches Columbia bob matches NYU.
I only added 2 ranks to the list b/c bob and anna matching at the same program was already included in the first example. If NYU and Columbia were the only 2 programs close enough for them to be apart, they would have a list that was 10 long.
3) Rank the programs that you have common interviews for first and then rank all the other possible combinations after. Since one of the partners can go unmatched while the other matches, this leads to a list of 120 ranks long.
Skunk: In regards to your question. What happens if you match your #1 and he doesn't match? To prevent you from having to scramble, one of your ranks should be you matching and him going unmatched. This should be toward the end of your list after you've exhausted all the possibilities of both of you matching. If this were to happen, I believe he would be allowed to participate in the allopathic match and you would have your osteopathic spot.
Redsox: ENT and Neurosurg are both tough matches to begin with so being able to match as a couple into the same program complicates things even more. Since both you and her are going through the match at different times you will not have the opportunity to couples match unless you take a year off or reapply after a prelim year.