Fr. Beaver always said there were three things you should think about before getting married, and I think the advice is great:
Is this someone you can’t live without?
Is this someone you want to have children with?
Is this someone you would be willing to sign your life insurance policy over to?
The latest of the three is particularly important for those in the military, but overall, I think the qualifications are pretty well-stated.
I don’t think that there is only one person who we each could marry. Love knows no laws except selflessness. But when all is said and done in a great marriage, there is a best person you can be married to. The person you marry for life is one who is necessarily the one God intended you to be with, and accordingly should be the most important living human being in your life. G.K.C. also obviously had something interesting to say on the matter, this in a letter to Michael Tolkien in March 1941:
Nearly all marriages, even happy ones, are mistakes: in the sense that almost certainly (in a more perfect world, or even with a little more care in this very imperfect one) both partners might be found more suitable mates. But the real soul-mate is the one you are actually married to.