Sometimes, when person A claims to love person B, some might say "No, person A, you don't really love person B." Often, they will back up this claim by pointing to aspects of person A's behavior as "proof" - i.e. person A is not jealous when person B speaks with members of person A's sex; or person A does not sacrifice a job opportunity because person B is opposed to the employer's ethical practices; or so on.
Does it make sense to tell someone that they do not really love someone they believe they love? After all, love is an emotion, and people external to person A's mind cannot properly judge the emotions person A actually feels. So what justification is there for judging a person's love on the basis of their behavior (setting aside cases where a person regularly beats or abuses someone they claim to love)?