I believe it is different for everyone. Some people (like me) get butterflies in their stomach every time they see that person, even after years of being together. When I see a text from my boyfriend, my face automatically lights up with happiness. When he is sad, I get sad, but I try to raise up his spirits. Being with that person and sharing a meal is possibly the best feeling you feel.

you just know. there is no definite way to tell. you just feel something like that person is right for you. i guess that is how you know.