The question shouldn't necessarily be whether or not long term marriage is possible, but rather is it desirable?
There are fundamental differences between the reasons for gettting and staying married now vs. in times past. Before it was more or less of an economic necessity for survival. Couples depended upon each other to perform complimentary tasks to maintain a household.
It is no longer that way.
SO why are people getting married now? For love and companionship. Which means, if the love loses its lustre or the companionship becomes unwanted, there is little holding the people back from finding more suitable companions.
Don't look at it as throwaway, see it as liberating. That way, if you or your partner outgrows the other, you don't find yourself stuck in a miserable situation.
Impermenence is inevitable and enlightenment doesn't always help a situation, as in a relationship of equals, it can bring in a teacher-student dynamic that the student very well might resent.
Sounds like you may want to not worry about getting married and start learning what makes a relationship work for you.
-cpc
