There is no such thing as a soulmate.  Oh, how some of you just bristled.  “Yes, there is!”,  you proclaim.  You will add, “My wife is my best friend.  Who are you to tell me different?!”.  Your wife may currently be your best friend.  You may proclaim her your soulmate right now.  Perhaps let me rephrase this, you don’t fall into a best friend or soulmate.  You earn and maintain soulmate status.