Of course there are exceptions to that rule.

Let me rephrase it once again:
If you look at it abstractly that is what happens. Cause -> effect. People think that how they react is a miracle and that relationships are some sort of magical thing.

However with a 5 minutes test where spouses ask each other questions from a sheet of paper and in turns answer it and both of them give them scores from A to C, psychologists can predict how many years (if at all of course) a relationship will last with 70% accuracy.

Of course if one of the probants gets hit by a car meanwhile everything can change about that.

Still;
They know exactly how that stuff works, that people in their everyday life experience as complete mysteries.
They might not understand it but they know it well enough to completely predict it.

They know it not by some sort of "street wisdom" or by looking into their own memories. They know it from going through cases in the millions.

Now, you might think you are an exception and you might be right.
Still to me trusting you on that would be stupid, because everyone does that, which is one of the results they got.

You might see love as some sort of mystery. It's more of a reflex. You do not learn love in many aspects. Often what you learn about love is hurtful to your relationships.
How you fall in love though is something like "getting a painful feeling when someone hits you on the head with a hammer". Guys fall for girls that like them almost automatically.
You can't pick if you want to feel pain or not, you can't pick if you feel hunger or not and you can't pick if you fall in love.

Simple would the world be otherwise.

Still it isn't so.

Now the girl can't control this either. That's the whole point to it.
No one can just fake it together all that easily.

You can both miraculously act it out like in a play.

Heck I don't say nothing extraordinary could happen.
Aliens from Tralfamadore might abduct you and hook you up with the most gorgeous girl of the world to study your sex life.

Don't bet on it though.

I am not talking about what I think, what is possible or other nonsense. I admit that it's always a trial to go out and make predictions from the past by analyzing data from scientifically conducted experiments.
However it works reasonably well and claiming to "know shit from experience" doesn't.