People are always changing. Especially early in life. If an algorithm can predict what you will be like in the future, now there would be all kinds of applications for that.
It would be something like, "You may not like this person today, but marry them anyway. In 10-20 years they will be your perfect soulmate." Now, how scary is that!
Agreed people are always changing and an algorithm wont predict the future, most likely ever, or not perfectly anyway. All we can do is enjoy and go after what we want in the short- medium term and if the happiness stays great, if not then you can always start over.