Not everyone's ready to settle down to a relationship, and some people won't ever be ready. That's just a fact.
If you don't want a relationship, though, you need to be up-front about it.
Tell your partner that you are only interested in dating at this time of your life, and then when he or she says, Okay, say that you really mean it. ("okay" is really "not when I get done with you.") If your partner says he or she feels the same way, that's perfect.
You don't have to do anything else, and you can keep dating that person.
If you are dating around, you should be careful and practice safe sex every single time, no matter what.
Guys, unfortunately, have a huge disadvantage here. Women are in control of their reproductive issues more than guys are, so if you're dating multiple women, you need to take extra precautions to ensure you don't get anyone pregnant. Condoms are part of the battle.
Being selective about who you date is another part; a girl who's had two kids by two different guys is a Very Bad Bet. Read up on things that make guys less fertile, too; two are wearing briefs or jockey shorts instead of boxers (keeps things too warm to make sperm properly) and using a laptop in your lap instead of on a table.
You also need to be honest about your habits. Let the women or men in your dating circle know that you are dating other people and plan to continue.
If they aren't okay with this, you need to extricate yourself from that relationship. If they tell you they're dating other people, however, and you're not okay with that, you need to stop and think: are you ready for a relationship with this person?
It's normal for men and women to be possessive, but don't have a double standard. It's not fair to the other person. And always, always, keep things open with your partners; if you contract anything, you will need to tell them immediately.
