If you are filing as Married Filing Separately then you do not need to list a SSN. You leave that blank (that's how I did it our first year of marriage, I listed his name but left the number spot blank)
If you are filing as Married Filing Jointly then you MUST have a SSN or another number (can't remember what they call it - ITIN???)
I didn't want to go through getting him that number the first year since his SSN was pending, so I filed separately.
The form really isn't made for people living outside the US.