Monogamy is not for everyone and that's fine, but other dynamics have to be done right. If polyamory and similar dynamics aren't done right you're breaking trust and possibly cheating. Polyamory, swinging, and open relationships can be done however you are comfortable with it — as long as it's talked about prior. Condoms and common sense need to be used during any of these dynamics. Make sure you are being tested and being safe. You also have to trust and communicate with your partner. Jealousy and certain feelings can come into play with any relationship or dynamics. Always talk and have a plan for when certain feelings come into play. What if you fall in love? What if you get jealous? Have a plan for all of it. Also have a plan for pregnancy and STDs.
So what are these dynamics? Polyamory can be done several ways. One of the most popular ways it's done is with a couple dates or having some kind of involvement with a person as a couple. The other popular way is where each person in a couple can have multiple dynamics or relationships with other people. By dynamics I mean anything from dominant/submissive, dating, or friends with benefits. A lot of people may not have any traditional dating relationships while poly. A few people may confuse polyamory with polygamy. Polygamy is more of a legal term for a multiple marriage. In the multiple marriage, the women traditionally don't get other partners like they would in polyamory. Polyamory is also known as the ability to love several people at once.
Swinging is having sex or playing with other people while still married or swapping partners with another couple. It's not for everyone and you have to be careful about it. Condoms and birth control are your friends in any of these dynamics but especially this one. You don't want to get pregnant from someone else who isn't your husband — maybe you do, but still you want to be safe.
An open relationship is very similar to poly. It's where you're in a relationship with the understanding that you're free to be intimate with others as long as you are open and honest with your partner. The only difference between poly and open is that in open you don't have to have real dynamics with others, it's just mainly sex or play.
Honestly, the main problem people in these dynamics have is with the judgement of others. I heard a poorly informed person who thought dynamics like these lead to STDs which we know isn't true. Monogamous people can also get STDs. Again condoms are your friends and so are tests. We have all been judged. I've even judged others or not understood how they could be happy the way they're doing their dynamic. But to each their own right?
One thing people ask is why isn't one person enough? It's not about that, it's about a personal preference. It can also be about not cheating or having fun. Being poly is fun, living life is fun. People excite me and I'm a nympho. Some people do poly or some similar dynamic because they can't do monogamy. Maybe they've been hurt or they are afraid they may cheat. Poly helps people have fun and a healthy relationship. They also do poly because they can love and care for more than one person. I was happy being poly because I was free and I didn't have to really answer to anyone like I would if I was monogamous.