How will you know that someone really loves you?

It depends, you should spend a lot of time together so you will know that.

i don't personally believe instincts can be trusted cause they are influenced by ur desires, and sometimes, ur desire may be far too great for that person that u might just get carried away and misinterpret every thing that person does. love can be expressed in one's eyes, smile, their level of care and concern for u, and the comfort and strength they feel when u r there beside them... i had seen one discussion called crush or love and i saw one person answering like this: Ask yourself this question: If the guy you're interested became extremely ill, or got injured and you had to do everything for him, feed him, help him go to the bathroom, etc. Would you stay with him? If the answer is no, it's a crush. If the answer is yes, then it's love.

You can't do any tests to find out, you just have to trust your instincts and decide for yourself whether tye really mean it of not. Usually, you just know when its rigt.