Tough to say, he might just be worried
about contracting stds if he thinks you
have other partners, then again, he might
be jealous, but unwilling to admit or
commit.
I would be thinking about myself if I were
you - by not "not using protection", i'm
assuming you aren't using a condom, but
you are using a spermicide or something,
no? If not, you should, vaginal
suppositories are unobtrusive, and can be
inserted some time before intercourse, and
there are other methods.
Personally, I recommend using a condom,
you can't be sure he isn't sleeping around
either - there is a female condom
available, but you might have to look
around for a while to find one.
I'd get this straightened out with him, it
doesn't sound to me like he's being
totally honest, either with himself, or
with you or both - you're both young it
sounds like, and jealousy isn't unusual,
even in a casual relationship - you need
to figure out what's going on in his head,
becasue if you meet somebody else, I
predict drama.
It almost sounds like he's trying to get
you pregnent, and in any case, males are
"programmed" in the evolutionary sense, to
assure themselves of paternity - expressed
as the behavioral trait, jealousy, which
is operant even if he's not trying to get
you pregnent (biology and cognition
operate on two very different levels).
Women tend to get jealous over resources,
and don't want a potential mate spreading
himself too thin in terms of
social-reproductive-sexual commitments -
again, expressed as jealousy.
So, in a sense, his behavior is normal,
biologically speaking, but questionable
from a social standpoint - he can't have
it both ways unless you let him, and it's
going to be up to you, it sounds like, to
finesse the situation and come to some
sort of understanding - jealousy can raise
testosterone levels in males, and lead to
more gonadal behavioral patterns.
He might also be worried about you - if
you're going to have unprotected sex with
him, it's not much of a jump to imagine
you might do the same with somebody else,
thereby exposing him to increased risk.
If he really just want's a casual
relationship, he should just use a condom
instead of forming what sounds like some
unhealthy obsessions.
Personally, i'd be looking for somebody a
little less possessive if you're just
looking for somebody to help you out now
and then, somebody who isn't averse to
taking reasonable precautions - or at
least threaten to - it's the times we live
in i'm afraid.
And it is a good idea to limit your sexual
contacts to people you know and are
comfortable with, but it can get
complicated if there isn't an upfront
understanding of what the parameters are.