How do I know if i'm really in love

I think many people can't make the difference between 2 things. 1st there is this feeling of CRUSH suddenly when you see a charming lady and you fell for her, and 2nd take for example 2 couples living together for decades with no worries and no signs of separation. I believe there's this big difference in these two types. The first isn't love at all as it's simply a feeling like male instinct. All males are attracted to females, that's nature. But to love is simply to co-unite for a better future. Correct me if ever i'm wrong, but the first type of attraction always dug me in mud.

I dont know how and when you know that you are inlove because the realization does not come overnight. It is a process that you would have to undergo and before you know it you are already inlove,