is this called jealousy?

So theres my friend...well i guess hes my boyfriend now :/ but um.. he likes me and said it himself, but i have another friend whos a girl and well shes a really good friend of mine.. they talk a lot and i just feel like he likes her for some reason. But then again he would have asked her out instead of asking me... im just confused about this, o yes and did i mention there is one more guy at our school who likes me. I just cant get the thought out of my head though.. I dont know if this is jealousy or if its just the truth because i honestly still dont understand how this whole thing happened...ive never been in a relationship before, and i just need an opinion on this...am i jealous? if i am then what should i do? should i ask him if he likes her?

Thank you...