Pro: Not having to answer to anyone about personal decisions.
Con: My family won’t shut up about me being single.
Pro: Nobody can whine at you about your weird habits.
Con: I miss cuddling.
Pro: You have all the time to yourself to devote your interest/hobby/passion in. Time to self-develop or to do things without caring what your partner will think. You have more money saved up to be able to enjoy activities or pick up things on the side. You have the freedom to meet and socialize with others at your own time. All choices and impacts made are the result of your own life and not taking the other’s mental/well-being in mind. You are free to choose any path you so desire.
Con: Once you’ve experienced what it’s like being in a relationship, it forever changes your brain pattern and when you stop being in one, that is when you learn what true loneliness is. The sudden feeling that life alone is not as great anymore. That is why you hear about how many people quickly find others as a rebound so they can keep their dopamine and serotonin high because those are the neurotransmitters that are involved when one is in a relationship and enjoy another’s company. Or when people end up taking drugs because some drugs can mimic the neurotransmitters of being in a relationship. (Look up fMRI studies involving love vs. recreational drugs, and you will see that similar parts of the brain metabolize with either one). In terms of loneliness, it’s a very severe thing that leads to degradation of mental health and that is why many individuals end up picking up hobbies to try to replace or repress that pathology.
Pro: You can do whatever you want, whenever you want. Want to go shopping for 2 hours? Why not? Too lazy to eat out/cook a proper meal for yourself? Just grab that can of soup and heat it up.
Con: No one to nerd out on things together like art exhibits and museums (these are things you can also do with friends, but sometimes it’s more fun with an SO).