Why is everyone asking me if i'm Bi or a ?? i dont get this!?

one of my friends, good friends knew her for about 3-4 years told me that she wouldnt be shocked if one day i came to her and presented her my gf and said "this is my life partner"! and a guy friend asked me if i was extremely sure that i wasnt a and today another guy friend asked me if i have never kissed a girl and if i'm not bi!!! i dont get this??? i asked him why he asked me that and he said it's because i say that some girls are hot and he feels so comfortable talking to me like a guy! dont get me wrong i'm not that girly but i'm not that tomboyish, i'm a healthy in between both!!! my exs used to ask me the same thing cause i loved protecting them and puting my arm around them, they told me i was the guy in the relationship??? i dont get this? does this scare guys away cause i've been single afor over a year now? what do u think, be honest but nice please :)