The original intention of the sentence "A smart person can't be a smart person without falling in love" is that smart people often avoid emotional entanglements, but if they meet the person you love, it is hard to avoid emotional entanglements no matter how smart they are.
This sentence can also be understood as that when you meet the person you love, reason and intelligence are often replaced by emotion, and it is difficult to make a rational decision. Therefore, when dealing with emotional problems, even smart people will encounter difficulties and need a balance between reason and emotion to make the right decision.
In addition, this sentence can be interpreted differently, and everyone can explain it according to their own understanding and feelings.