For me... its beyond the first couple of dates. Relationship is physical/sexual. Its great to be together. And its always exciting to be together. Lots of laughs. Lots of fun doing things together (not just the sex!). You open up to them about you, they listen. They open up to you about themselves, you listen. You laugh, joke, have more fun. You become part of eachothers' lives in some way (go out with friends, FB page pics, whatever). And then... one of you says it. Sometimes with a card or text first. Its a f'in cool & amazing feeling in you beyond words.
Sometimes you just feel it. They don't even have to tell you; you just know. Other times, you start of as friends, you may even date a little, and one day it just...happens. It depends on the person. The way they talk to you. The way they act around you. The way they look at you. When it's time for that person to say it, it will just happen. But...if you are feeling like you are falling hard for them and they don't seem to care, it's a different story. You should probably sit down and talk about where the relationship is going. Just my take on it! Sorry for rambling >.<
By the way they treat you. If they show you attentiveness and genuine care, you can tell. Don't ever go by what people say to you...people say a lot of things they don't really mean. Let them prove their love through how they act towards you. ACTIONS > Words