You might have heard that women get more attached after sex than men do, but that’s not actually true. No matter your gender, hormones released during orgasm, including oxytocin, increase bonding, which can make you feel closer to and more trusting of your partner. Research has shown that there's an overlap between sexual desire and emotional love in the brain's insular cortex. So, love and lust are definitely different entities in your brain, and they can overlap.
Just the act of being sexually vulnerable may produce a connection for some people. And some people may incorrectly interpret these feelings of connectedness as deeper than they actually are, or they might "mistake" the feeling of being physically close and the feelings that come along with that, with an actual, real connection.
Often, what's really at play when we talk about sex and emotion is one person's ability to be vulnerable to another person. An individual’s ability to separate sex and emotion correlates to how you feel about sex, how you think about sex, and how much sexual experience you have. If you're someone who hasn't had a ton of sexual experience, for example, you might feel more vulnerable about your hook-ups simply because there's more weight to them. Then again, there are so many factors that go into how one person feels or thinks about sex, and everyone is different.
There's no right way to view sex and emotion because, ultimately, you should do what works for your relationship and makes you happy. Non-monogamous people might find that it's best to have separate partners who fulfill different emotional or sexual needs at once. Ideally, you're practicing consensual non-monogamy (CNM). Those in monogamous relationships could have passionate, emotional sex one day and then fiery, emotionless sex another day. Being mindful can help remove performance anxiety during sex, which can allow us to be more sexually free and take off the pressure we often put on ourselves during sex.
No matter what the terms of your relationship are, you should communicate about your desires and expectations before you have sex and continue to communicate about them as the relationship continues. That doesn't have to involve any sort of grand statement, but if you tell the person you're hooking up with what you're looking for, that will save you a lot of headache and potentially heartbreak down the line