Girls are more jealous. Fortunately, I'm not one of those girls burdened by being a jealous person. My boyfriend doesn't have a lot of female friends, but I have no problem with the ones he does have or him spending time alone with them. He has no problems with me spending time with my guy friends alone either.
I think that if a relationship halts friendships, it's a relationship worth looking deeper into to see what other possible abuse factors it carries.
Personally, I think guys should be able to hang out with his guy friends as well as his girl friends and girls should be able to do the same. But when there is no trust in the relationship then that's when it becomes a problem. Oh and yes I agree that girls tend to be a bit more jealous but I've had guy friends in the past that were super clingy and jealous when I hung out with other guys!
I think that if a relationship halts friendships, it's a relationship worth looking deeper into to see what other possible abuse factors it carries.