He gives me so much attention and love and refers to me as his "wife" and wants to marry me.. but when I wrote "i love you" on his FB wall.?

Yes, you should worry. A guy that didn't want people to know that he was involved with someone would do something like that. That or he's just using you. Deleting it was disrespectful, hurtful and very cruel. You need to find a boyfriend that is not ashamed that you write I love you on his Facebook.

***Edit***

His Facebook is for family and friends and you. There is something wrong if you can't tell him on his Facebook that you love him. He should be proud instead that you had said that. What is he hiding from you that you can't tell him that you love him on his Facebook? Who is it on his Facebook that he doesn't want that person to know that you love him? That is the questions that you need to ask yourself. Telling someone that you love him is supposed to be good. But the way he reacted to that is that it's bad that his family or friends know that you love him. I think you know what you need to do.

How long have you been going out with him?

so my boyfriend... he refers to me as his 'wife' he begs me all time to marry him, and constantly gives me attention and affection and I never ever question or think there's a problem... UNTIL I wrote on his Wall on FB.... I wrote "I love you" .. or something similar. he DELETED it:( I now feel :( he tells me he doesn't want his FRIENDS to annoy me or hit me up on FB and annoy me... should I be mad? worried? am I asking too much?? he gives me SOOOO much affection.. I just wanted to give some back.. and when It was shut down it really hurt!:( he spoils me with attention.. so... I just wanted him to FEEL my love.. i should worry, right? for him not keeping it on there??:). We have not been together too long.