How to know whether someone going to be my wife or not?

I am 32 years old. Looking for the lady partner!
I met some girls from matrimony apps. Some of them were just calculating, while 2-3 girls were interested. But unfortunately things didn’t work out well. I don’t know how anyone love someone before getting married if it’s taken like a corporate deal.
My younger brother is getting married in 6 months and I haven’t even found a girl for marriage. I don’t know where I am doing a mistake?