A soulmate it's like a best friend, but more. It's the one person in the world that knows you better than anyone else. It's someone who makes you a better person, well, actually they don't make you a better person...you do that yourself because they inspire you. A soulmate is someone who you carry with you forever. It's the one person who knew you, and accepted you, and believed in you before anyone else did or when no one else would. And no matter what happens..you'll always love them.
Can a marriage go into its golden years without being soul mates? The answer is no. A soul mate is a development over time, and in some marriages, the identity developes much earlier. Last year we visited a friend in the hospital after having a massive stroke as he laid there unable to communicate his wife was reading his mind and movement. So I asked her how do you know what he needs. She knew the motions, timing and looks that were incoherent to everyone else but her.
Soul mates are by timing and chance; can there be divine intervention of course. Do they still have disagreements, of course. When do you know you are soul mates? With time and circumstances as our friends displayed when you can communicate in silence, when you move proactively to care for one another.
Many want to think there are no human indiscretions, meaning behaviors or speech that displays a lack of good judgment. Those still exist but soul mates will work it out. Soul mates never divorce they progress.