It's not the fact that your old enough. It's the fact that your sleeping in the same bed. Some people will find it inappropriate regardless your age, especially when your not married. If you are at your apartment you sleep on the bed and he sleeps somewhere else. Okay then. Thats good boundaries being set up. The same applying if your stayed over with him. It's not about being an adult, and it doesn't make you an adult. Nether does your age. It's using common sense and having respect for one another. If your parents did find out, they will be in a disagreement with your relationship. You maybe 21, but you still have to honor your parents. And hiding truth from them will only hurt and strain your relationship with them further. You need to know where your values lay at for yourself. And religious has nothing to do with it. Question every and anybody who did what you did and see how far their relationship goes, or have their ever kept their partners, or led to marriage without a divorce for life. You don't want to compromise your values and wants if its not something you know you don't need. That's what you need to think about. And what are the consequences that comes with such a choice long term, not just short term. It all boils down to choices. And if your out of your parents home, officially, you need to think about this for yourself now. Because it will come to a point where no one will able to help make that decision with you, and you'll be by yourself to make them. Also ask yourself this: Am I going to regret it? Hopes this helps.
It's entirely appropriate! You are an adult living away from home in your own place, and this is what adults who have their own places do! Don't feel bad about this. Your parents might not approve but you are going to grow up sooner rather than later and they cannot dictate how you live your life once you've moved out.
i dont see what sleeping is significance.. if you're having sex thats different but then you are an adult so it shouldn't concern them. as far as sleeping over, its a totally common thing in uni. everyone crashes at peoples places. just more convenient then going back home deadening where you are. if your parents will flip then dont tell them, but they need to chill.
hahah i felt the exact same way when i had a guy sleepover for the first time too. my friends all laughed at me. anyways, no it isn't bad at all. my parents are the same way- they won't let guys sleep in the same bed as me under their roof. However, they don't care if i spend the night over at my boyfriends house/apt.