They are willing to give, or at least share, the last slice of pizza. You are not afraid to be yourself around them — your strange humor, your occasionally awkward mannerisms, your interests in things that other people might consider a waste of time. Even if what you like might not be their favorite thing, they are always willing to give things a try if they are important to you.
Miss u so much! They surprise you — and not just with random gifts of flowers or chocolate.
They are evolving into a better person from being with you just as you are with them. They are just as capable of having a ridiculous night in, eating junk food and watching crappy TV, as they are of shining up and attending an important event.
You are capable of both doing your own thing from time to time without the other becoming irrationally jealous, suspicious, or angry.
There is never any doubt that they are thinking of you, that they consider your feelings, and that you are important to their life. You both have generally similar visions of the future, and what you want out of life. If you suffer a moment of weakness or need help with something, they are eager to support you and not shame you for being incapable of handling it on your own.