Thinking outside the box of relationships
There are lots of relationship options that you might consider. The basic break-down is probably best known as monogamy (meaning you only have one sexual partner or husband/wife) at a time, and non-monogamy but it is much more complex than that. Non-monogamy is an umbrella term that covers;
Polyamory, Open Relationships, Fuck Buddies, Friends with Benefits, Triads (and Quadratic, etc.), Circles
Again though, these are just umbrella terms that are more useful when trying to explain your relationships to other people than they are when looking at what your relationship is. Below I will talk about these in a bit more detail.
Like many people, when I was growing up I was only really exposed to one type of relationship. That was monogamy, and it was mostly heterosexual. I always felt as if that was the only option for life; at some point, I would meet a nice boy (never a girl) that I liked, and if he liked me too, we'd get married. Except about 90% of the people I knew who had followed this path ended up divorced. That just didn't add up to me and by the time I was 20 I was sure I didn't want to follow that path. I conceded I might still meet the nice boy but there was no way I was going to marry him, what was the point.
I spent most of my twenties trying out these boy/girl relationships, that always crashed and burned. Finally, when I was 35 I started a new chapter of my life, and suddenly I found that what I'd always been taught (not through explicit tuition but through societal conditioning) wasn't actually the only option. There were other ways to do things, ways that better fit with how I wanted my life to be.
The Oxford English Dictionary defines a relationship as:
1. The way in which two or more people or things are connected.
2. A loving and sexual association between people.
I think when looking at relationships it is important to also include friendships, not just because they can be sexual in nature but because to me they are an inherent part of my life. I get just as much from my platonic friendships as I do from my non-platonic ones. And to a large degree my friendships feed into my other relationships.
There seem to be a few ways people do open relationships, to me this is when partners in a 'primary relationship' are free to see other people as well. There are various ways to do this, it can either be a blanket consent thing, or you can decide you need to check in with your primary partner each time. You may decide one night stands are fine but long term isn't, or vice versa. You might decide to join a swingers group, and only play with other people when you are both present. There are so many ways you could open your relationship, and I think it is very important to decide what works for you and your primary partner.
Then there is polyamory, to me this is when you have more than one partner but again it can be flexible. It may be that you are in a threesome or foursome, permanently. You share your lives in a group. Or it may be that you have two partners who each have other partners, and you keep each partner separate. You may also decide to add someone else to your main relationship, someone who plays with both you AND your partner.
You may be non-monogamous without a primary partner but have friends with benefits (good friends you have sex with but with whom you are friends first), and fuck buddies (people you have sex with sometimes but don't really have any other relationship with). Or you may be non-monogamous WITH a primary partner, and you both have friends with benefits and fuck buddies. There are so many relationship options, and I don't even feel I have touched on them fully here, I haven't mentioned bisexuality, or gender-queer, or any of the other factors that will come into play when you are deciding what type of relationship is right for you.
It may be that you are in a monogamous relationship that works for you, and if so that is great. However, that's not always the case. It might be that you love your current partner very much but that the relationship is just not working. You don't want to leave them but you need more than what you currently have. If that sounds familiar, please know there are other options. Talk to your partner, discuss other ways relationships can be, maybe do some research into the mechanics of different relationships. There is a book by Dossie Easton and Janet Hardy called The Ethical Slut which would be a good place to start your research, as would Intimate Friendships by Dr James Ramsey.