Can you be in a relationship and still keep your close friendships with the opposite sex?

This is a question that most people, who befriend the opposite sex, battle with when involved in romantic relationships. I am the type of person who has always had more male friends than female friends. The reasons why are many.. but this blog isn't dedicated to address that. Lol.. to the point! In my opinion, male companionship is a lot less falsified, so I gravitate towards males faster than I would to females. Some may question this but I stay true to myself and that's what matters. I'm not gay nor close to being bisexual, so let's get that straight.  For as long as I've been dating or courting guys, which hasn't been for too long (I was a late bloomer), I've always kept my friendships with the opposite sex isolated from others. The reason is this: most men are jealous. Most people are jealous by nature "yes", but men show their jealousness in a way that is more "manageable" and readjustable, sort of speak. Let me explain, I've had male friends who, overtime, declared they wanted to be more than just friends while I was in a relationship, but with my displayed loyalty to the person I was with, they were able to withdraw themselves from the idea that they needed to give up. It took much effort from me, and who knows whether or not they actually surrendered but the fact of the matter is I demanded respect for my relationship. That's what's important in any relationship. Many of these friendships I still have and continued to have, but rest assured there was still concern from my partner. I'm not saying its easy to manage both but real friends show respect. Please share your opinion..