The truly ideal partner cannot be imagined b/c we don't know what we want until we experience it. Sure, there are ideal physical and mental attributes that can be assigned, but will they a part of the person who is best for you?
The ideal, perfect person will surprise you, will intoxicate you with mannerisms alone, will be a necessary part of life. I can only guess at the form and content, sure, an educated guess, but who really knows.
The ideal, perfect person is who we end up with, but if kids are a must that may not be the case. And, then again, we may never end up with anyone.
So, in conclusion...