This reply is focused on romantic love. It depends on how you define "real" and "permanent." You might love someone sexually and romantically at first and then the love might change into another form- friendship, acquaintances, etc.
Love is real by default of you having felted or acted it out, rather than because it lasted in a single form permanently.
Personally, i think it is a pity to (romantically and lustfully) love only one person throughout your life. If there is a wish i have for people is to love many and enjoy each love as it comes and changes. Being in love and the excitement of feeling loved and loving is paramount; heart breaking sometimes, but ah, what a rush.
i do think that once you love someone it is difficult to not love them, your love changes. You might not want to be in their company ever again, but generally, you do not dis-love someone. Having said that, there are always exceptions to the rules.
So, to answer your question- i hope it is not true that in order for love to be real it needs to be permanent. i hope that we love more than once.