Every relationship goes through a monotonous stage. Every couple went through it or will go through it. No exception. If you are going through the dull phase right now, I might be able to help you. My help comes as a type of suggestion. Will you go with it, or do you decide to skip it, it is on you? From my personal experience, I will suggest a threesome romantic ethical porn. Most people fantasize about romance video sites.
If you don't think about it, then I don't know what your problem is. I am kidding (not). I can bet you at least once in your life watched threesome couples cinema sex. When you are watching ethical romantic porn, you must be thinking about how gorgeous the actresses are, how the scene is hot, and how they do everything with ease. But, when you start to think about how it would look in a real-life, things go downhill fast. Of course, couple cinema porn can be a fantasy for masturbation. It's much easier for us when we picture how we want things to happen in our heads. In the real world, things are a lot more complex. Some people think they would slay a threesome because of the porn movies, but they are wrong. Things escalate fast in regular sex, not to mention when you want to add a third party.
Luckily for you, if you are looking for someone to be your third man or woman, there is a platform called Feeld. There you can find someone to spice your boring sex life. Also, if you have any kinks and fetishes, the market on the Feeld is enormous, so choose what you like. Now when I think of it, it reminds me of Tinder a lot. Not the casual date in two, but a three-way date. So, if you are looking for someone to swing with, hit your app store now. Another option is less pleasant. You can search in sex forums or go and visit your nearby sex shop. They won't hook you up with someone. They will probably inform you about upcoming swinging events in your area.
You are well aware that you need to set some rules regarding a threesome. What will those rules be, it depends on you. Maybe you don't want any dictum, who knows. But, if you ever decide to go to a real swingers' party, you have to pass the STDs test first.
After spending some time in swinger water, going from one event to another becomes boring. Even if it does, don't stop with it. Think about changing the scenario. You can always host a party at your house. I don't mean you should call like thirty people. Put a list of couples you feel most comfortable with and swing it. But, make sure to provide your guests with essentials. For example, condoms, sex toys, and cleaning wipes. And, don't forget the food and drinks. My suggestion is to ban alcohol from this type of event. You never know when someone can become violent and aggressive.