Hey, Malia. I'm just seeing this but I also, unfortunately, have to head out of work for the day. I will make a point, though, of coming in first thing tomorrow right here so you don't have to wait on me for more help. I hear you about what can happen when there's distance in a relationship, and what has felt like it was missing for you, we can talk more about that tomorrow, amongst other things.
In the meantime, I want to quickly make clear that almost none of us will love only one person in a lifetime, not if we're lucky, anyway! Most of us love at least a few different people in a few different contexts, and just like some of us have a few friends who we love, some of us have more than one sexual or romantic partner we love or are otherwise engaged with. There's no right or wrong to any of this, it's just about what's right for a given person and the people they're involved with. So, even if it turns out monogamy isn't right for you, or what you actually want, be it now until the end of your life, or for some phase of life, that really is okay.
That said, I want to share a link to a series we have here about poly just so you can get a look at it and have a sense of how you might be feeling about if an exclusive relationship is actually what you think you want at this time of your life or not. I think having a real sense of that will be pretty important when it comes to deciding how you want to approach some of this:
https://www.scarleteen.com/read/relatio ... mory-guide
Lastly, real quick: it's never a good idea not to use safer sex or to go without contraception with a new partner. For once, you don't know this person well, so who knows if they are being honest with you about their sexual history or not. But even if and when someone is, we need about a six month period between sexual partners, paired with testing, to even know what our status is when it comes to any sexually transmitted infections. If he currently has other partners he's actively with and he is not using barriers with any of you, or hasn't, then I'm afraid you may well have been sleeping with someone with quite considerable STI risks.
That's why we always advise all new partners practice safer sex for at least the first six months, and at least until both partners have a new, full STI screening they can share with each other AND then only stop using barriers if and when they are only going to be with each other. People who have more than one partner at a time, or who have very recently had other partners should keep using barriers until it's been at least six months without another partner in the mix AND with new STI screenings that show no active infections*. So, if you sleep with him again, do yourself and your health a solid and be sure to use condoms for any vaginal, anal or oral sex, at a minimum, and yes, you will want to schedule a screening for yourself in the next 4-6 weeks (not right away because of incubation periods). <3
* This is sometimes not as simple as that, just to be clear. For instance, if one or both of you gets a positive for something treatable, then you'll want to get treated before any more sexual contact, even with a barrier, ideally. And sometimes, people will test for things that can't be treated or cured, like HIV, HPV or Herpes, in which case it's then a discussion to have between them and any/all partners where everyone just decides how they want to do things with those infections in the mix.