Different people are different.. most modern young people expect to be able to have friends regardless of gender, but that certainly is not the case for all.
Older western generations were much more segregated by gender in relationships.. even in the UK if the couple had friends, it was normal that the man would keep in touch with the male friends, and the women would keep in touch with the female friends, and they would not see the oposite sex friends alone unless there was a specific need or different circumstance (say they grew up together and were like family etc)
This is still the case in many societies around the world..
Its perfectly ok for a guy or girl to hold this attitude. Although its not normal, if that is their expectation of a relationship, then thats ok. The problem lies when you have two people who don't agree. If you have one person who has this far more traditional view of male/female friends.. and one person who is much more modern in their outlook, then its going to end badly. One of them will have to change, and it will lead to either resentment or jealousy.
I would suggest, if this becomes a real problem, then your relationship is better off ending, and you are both better off finding new partners whose attitudes towards relationships are more in line with your own.
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I hate it when I see a lot of very negative things said about boys such as your boyfriend though, as its a fairly common expectation that is equally held in many girls. Its nothing awful about him, but just something that may show that you two are not compatible.
Me and my wife are both quite conservative/traditional in our views of friends, and it works well because we share those views.. Old friends we have known for years are ok.. but when we make a new friend together as a couple, I tend to keep in touch with the boys, and she does the girls.. We both quickly realised that we were not overly comfortable with me going away and spending time together with other girls, or her spending time together alone with other boys..
Some would call it a lack of trust, but I would suggest that anyone who claims to have never gotten jealous in a relationship is lying to you, or to themselves.. its natural that we all get a little jealous from time to time. Keeping a little more oldfashioned view of friends is a small sacrifice to make our marriage nice and smooth and jealousy free... and its worked great so far! We have lots of friends both boys and girls who we see all the time, but its all done in a way where we both know exactly what the other expects and where we stand.