What is everyone looking for in a partner?

My boyfriend and I broke up, and now we're casual. I'm not upset and neither is he, but he's several years older and I'm about to hit my 20s. It made me wonder whether every guy is on the search for 'the one', and whether I'm one of many who aren't looking for anything serious. I suppose that's what went wrong, we wanted different things. Is it a bad choice to put us on a casual stance now?
But, how are you meant to know whether someone is looking for something serious, or something fun and casual? And how are you meant to gauge that when you first meet a potential lover?

We're simple. Forget the games, just straight-out ask whether it's serious or casual. That's what I do to girls once it looks as if we're starting something out together.

And going casual after breaking up is something I'd advice against, it basically means that the guy wants to still reap the benefits but with zero responsibility, and if you're emotionally invested you want to move on rather than cling onto false hope.

"...Is it a bad choice to put us on a casual stance now? ..."

If that's all you two want and need at this point, then it's not bad at all. You don't want all the baggage (good and bad), but do want the companionship. Having a fwb is usually better than a series of one-night stands.

"...how are you meant to know whether someone is looking for something serious..."

Communication. Lipp's absolutely correct there. Plus, feelings change so keep communicating. Tell him what you like about him - people love to hear that, though in more modest people it can cause some discomfort too. Also tell him something like "I'm glad that our relationship is X right now - that's really what I need and am grateful you can give it to me."

"...how are you meant to gauge that when you first meet a potential lover..."
Quite simply, you don't. Likewise, that lover (should) understand that the early times in a relationship are not meant to find a life-partner, but are meant to weed out the jerks and psychos. After you get through some of the initial "I'm infatuated and want to know everything about you" phase, THEN start talking about where you want things to go.

"...whether every guy is on the search for 'the one'..."
Guys are all different. Some, from the start, are looking for wife and mother. Others go through their entire life never wanting long-term commitments. A caution I would give, too, is to avoid the whole "soul-mate/the-one" trap. It can lead many to turn their back on good people due to small flaws, and can cause distress when perfection is elusive.

-PP

Not everyone is looking for the one. I think one of the biggest issues with relationships is that we pair up based on physical attraction, chemistry, things we have in common etc. But we don't investigate deeper into our compatibilities. We don't look at the long term. If you want a serious, lifelong partner, you need to ask these questions early on. If you want a casual relationship you need to ask this early on. Lol, I know it sounds a little weird. It doesn't have to be awkward, you don't have to ask it dircetly, but if these are things you really want to know you have to ask the individual to see how they feel about it. Hope this helps a little.