Hello closetoyou , "I can't help " means I can't abstain from doing something, not being able to stop or control something. This expression is always used with the negative. " I can't help falling in love with you " means I can't choose not to fall in love with you , because the feeling is probably so strong, that is it almost uncontrollable . It is like the person is resisting to fall in love but can't . Another example: " Although she knows she has to loose weight, she can't help eating pizza and chocolate. " She can't stop eating them, can't control her appetite. This expression is sometimes used in the form of: " can't help but do something" "I can't help but fall in love with her".

I just want to add that it is an idiomatic expression. It is used, as Cherry said, to say that 'it is impossible to prevent or avoid something': 'I can't help falling in love' = I can't stop myself from falling in love = I can't avoid falling in love = I can't prevent myself form falling in love You say it when you are deeply in love and when you are attracted to somebody. That's why it's impossible to stop yourself from falling in love. Other examples: I can't help feeling depressed sometimes. I couldn't help being nauseated by the violence in the movie.

In this case for example : " Neal can't help but agree with my answer ". Kidding ;)

I thought I had the answer, then realised I had not read the question properly but can't find a way to delete my response, so... I agree with Cherry's answer!