Is girl/boyfriend important when you have a lot of best friends?

No. If anything it makes life harder because you have to manage time with your girlfriend as well as all your friends and if you have a jealous boy/girlfriend, then it can be even more difficult. However, this shouldn't stop you from dating someone if you chose to.

an intimate relationship is pretty different from a best friend. It's not like 4.3 best friends is equivalent to an intimate relationship. there are things that go along with a relationship that are not a part of friendship (and I am not talking sexually). As far as is it important, that should be left up to the individual, going through life feeling social obligations to "have a girlfriend" or "spend friday night out" can be destructive to a degree. the reasoning for your actions should come from within, not from what you think others think is best.