Does love exist before marriage?
As for the answer to that, Yes. Islamically, It shouldn't, coz ur not supposed to have contact with the non-mehram and that, but nevertheless, it DOES exist before marriage.
How do you know it's love? Well....You just know. It's a feeling apart from all the other feelings than you've ever felt.
There are different extents that people can go upto, in different types of love:
a)There is being patient in love, and waiting for the person.
b)There is talking to the person on the phone, texting, etc. and you feel as if you cannot live without that person.
c)Some people (Astagfirullah), go upto the extent of harming themselves, inflicting self-harm, and even going on to commit suicide, because they cannot wait for that person.
Oh I dunno lol I've tried to explain it as much as I think I could.... *rollseyes* but I think you get the general jist of it....