How long should I wait for those three words?

My boyfriend of six months is sweet, attentive, and honest with me. It bothers me that he hasn't told me he loves me yet, however; is it out of the ordinary for men to wait a long time to say this? He talks to me every day, takes me out, gives me compliments, and tells me he "adores" me,but no "L" word. Should I stick around and see if in the next six months or so he decides to tell me? Does it take men longer to decide? Or is this a warning sign?