Stealth: I agree that a relationship based on sex alone is not necessarily going to last, but in a marriage it is very important, even as the apostle says: "Do not be depriving each other of it." People's sex drive differs from person to person, so there may be problems within this area. It is not without good reason that we find in the Bible different types of 'love'. For instance, the love that parents have for their children is different from what they have for each other. The physical act between marriage mates can build up deep affection, simply because you are in a sense exposing your very soul. You can be at your most vulnerable, therefore if you truly have affection for your mate in the first place, you can achieve a greater depth of trust and 'integration' of the two souls.
On the matter of having two 'classes', I see that there could be a problem based on our current frame of reference, but I am not shy of using the term 'wait on Jehovah', for what else can one do. Part of faith in God is 'trust'. In fact the very word faith is synonymous with trust. So a Christian does well not to worry about things like this, because they are beyond his/her control anyway. Just trying to be encouraging to anyone who is concerned about this. I left off worrying about this many years ago - and it did concern me very much I can assure you!