I think you should instantly have fun, connect with each other, ‘get’ each other, and you should feel valued and respected and listened to. A lot of it is just finding a really good friend, but one you share similar values with and life goals. But I don’t think you’ll ‘know’ all or any of that initially. Mostly it just shouldn’t be hard work and you shouldn’t have to think too hard about it.
When I first met my husband, I had absolutely no inclination that he was ‘the one,’ in fact it was absolutely not something I considered at all for about 6 months. I had many serious relationships before him (when I did instantly wonder if they were the one), but I was just not at that place when I met him. We were both working abroad in a very small expat community and there was also 7 years difference in our ages (I had just turned 28 and he was 21). To me it was just a casual thing that would end when we moved home the next year. It stayed relatively casual for 6 months and then we went through a really awful series of events together (nearly being caught up in a terrorist attack, another frightening and violent incident directed at both of us, working with the police and legal ramifications from this, some immigration issues as a result, all in a fairly challenging developing country). It was just a really frightening, stressful couple months but we did it all together. I think we realised this was it for us when we came out the other end stronger and realising that if we could survive that and be closer than ever, then we could survive anything (including several years of a long distance relationship, we lived in opposite sides of the world). I don’t know how long it would have taken us to see this under normal circumstances. Maybe we wouldn’t have? I don’t know.
But we absolutely did not feel that way to start and not for 6 months. Mostly we just were really good friends and had more fun with each other than anyone else. And I think key for me was he was dependable and was who he said he was and did what he promised. If he said we’d meet up after work, we did and he was there on time. If he promised to text me when he got home, he did. If we went out, even in a big group, he spent the evening with me, like he didn’t wander off getting other girls numbers or disappear or ignore me. If we made plans to go do something at the weekend, he never cancelled and was there to pick me up just like he said. That’s the only thing that I genuinely noticed was different from any other guy I’d dated from the start.