Sex is a natural urge, but people don't necessarily require it to maintain relationships.

It's called companionship love. Like old married couples for example, they have no sex (well, less than before, and much more tired... I guess), but their lives have been co-dependent. They require and love the companionship of the other person.

People always move on from romantic love; they either move on to companionship or find someone new to have a steamy romance with.

 Only one way to find out. Let's see if I can find a knife.

I would. Feels nice having that other someone sometimes.

I almost think it would be easier, if emotional bonds were emotional and sex was just sex, that society wouldn't place so much emphasis on having both together. Granted, many people live that way now, having friends and casual sex as totally separate things, but still...

 maybe it would be better if we all just lived like wild sex monkeys and had sex with everyone, like animals do.

 I agree, at some point in live I realized this was truth. I love sex as much as the next guy, but having someone by your side is amazing. 

I'm not much for casual sex, but at the same time, I've never truly wanted any sort of deep relationship with a female that I didn't want to have sex with.

I suppose it is nice for some to have someone by your side. I personally have grown accustomed to being alone most of the time. I find people, especially in close situations, to be annoying. I feel the need to be social very rarely and when I do, it usually involves casual engagement just going with the flaw. When I want to deeply think or feel like entertaining myself, I find being alone is much better since I can fixate on myself.

Well don't people have best friends of the opposite sex?

Straight up no, just chill with your friends and spend your money