
I see that makes sense then. But I think calling them 'love' marriages isn't accurate, perhaps something like Unislamic marriages maybe? Because Islam accepts that marriages can happen between two people in love, as I showed in my previous post with the hadeeth.
Firstly, you need to understand that 'love', you can't really explain it or rationalize it. It's an emotion and it can't be put into a defined set of rules that says this is how it happens or doesn't happen. It just happens because we have no control over our hearts. This is exactly why it isn't haram to be in love, because it's an affair of the heart and you are not accountable for how you feel towards br. x or sr. y, you're accountable for how you react to your emotions.
I could give you many possible ways people can get into love. It could be a glance, association in halal places such as classes or organizing community events etc even if it's completely serious and only when needed. I mean you can't really explain it, but it does happen and can happen without the two people engaging in haram activities. Ibn Hazm gives a few chapters on the ways people can fall in love, interestingly he even says people can fall in love in their sleep. He says:
Love indeed is sometimes caused by things so strange, that but for having myself observed them I would not have mentioned them at all.