whats it like to live with a man?

Your boss is caring and that is what is attracting towards him. On other hand at 36 he is taking advantage of 15 year old.
Take care of yourself. There is lot in life stored for you

Olive, you're only seeing what you want to see. People are trying to tell you that having a relationship with your boss is inappropriate. If he is looking at your lingerie when he thinks you're asleep, and if he is sexual with you in any way, this is wrong. You are 15 years old and have no business going after a grown man.

you said you just wanted to know what its like to be with a man but all this thread is doing for you, even though people are trying to help you see the reality of your thinking this way, is encouraging you to obsess about him in unhealthy ways. this is not healthy dreaming. but it doesnt really matter what people say, you don't want to know what is healthy, you just want to obsess because you are addicted to what you feel when you think about him. it has nothing whatsoever to do with him. in a fantasy world that you want to lose yourself in, its easier this way than facing reality - for that you need professional help in order to have a healthy relationship because of where you are going in your own head. if only your parents could see what is happening to you...maybe they could get you some help.

my stepdads new so he's not really my parent, i never met my dad. mum is too obsessed with my stepdad and i'm too obsessed with my crush. but like even before my boss i had crushes on older guys but at least now its only one guy and not 3 crushes sorry i can't help how i feel

All of it is normal - in the past, women your age got married, on a routine basis. This was because women were expected to do housework (in lower classes), or host parties (in upper classes), and you can do all of that at your age. Physically, you personally have developed enough to have sex.

Men have traditionally had a much higher median age of marriage, for reasons that were mostly economic - men were supposed to be bread winners and needed to establish themselves as income providers before proposing. As a separate fact, men often go through puberty later, although not by much.
Puberty - Wikipedia, the free encyclopedia

So all your feelings are normal and not to be worried about. The situation that you are in is an artifact of your living in Australia in 2013 - your living in Australia makes you under the legal age of consent, so the boss is afraid of legal consequences. And he should be afraid of legal consequences. But the responsibility for his actions is entirely on him - you do not have any responsibility at all. The age of consent must have been instituted in Australia in an effort to PROTECT you, and not in an effort to restrain your behavior. And, of course, not to change the way you feel - I am sure that there is nothing in Australian law that would attempt to change how you feel.

i feel guilty when he shows affection to me like i'm cheating n my boss

That is very common - an ill-conceived sense of loyalty. Believe me, it is a very negative approach and it ruins what otherwise can be a good time, makes you forego opportunities with perfectly reasonable and qualified men, etc. etc.

It took me many years to figure out how pernicious this approach is.