Is there a way, a trick to know if a person really loves me or they are just taking advantage of me?

So your idea of love … is to perform a test on someone without their knowledge?

Good luck not getting dumped with that strategy. That’s deception, and it’s not a very loving thing to do on your end. That’s the “if you really loved me, you would …” school of thought. You might want to transfer to another school. If you’re only trying to find out if you’re desired and don’t care about the consequences, then, by all means, employ a “trick.” If you want them to stick around, make sure they never find out about your fucked-up experiment.

I guess the hidden questions are these:

1. Why don’t I trust the person who says they love me?
2. Do I love the person who professes to love me?

If you’re getting signals that the person who says they love you is trying to use you and doesn’t really care about you, you could ask something like “I’m getting signals from you that contradict your declaration of love for me. Would you care to explain them?” If the answers don’t satisfy you and/or if their behavior continues to be the opposite of their professed love, feel free to dump them. No deception is necessary.*

If you love someone but they don’t fit your criteria of an acceptable friend/partner, then let them go. Don’t waste your time on someone who doesn’t want what you want and would ultimately be a disappointment to you.  If you don’t love them, why do you care if they love you or not?

* The addendum here is for an abusive/violent/dangerous person. If the consequences of requesting the truth will be used by them as an excuse to hurt and/or attack you, feel free to be as deceptive as you need to be. The “trick” in this instance is focused on maintaining your safety, not simply trying to catch someone in a lie.