lost love

You meet someone special (unlike anybody you've met before), the connection is more than just physical, you become best friends, things escalate quickly and then you realise you could even be soulmates (if you believe in that) you fall in love and become lovers but then things end as quickly as they started. Ultimately, my question is - Is it unreasonable to NOT want to stay as friends ?? Is it bad to want to just cut them off completely and move on with your life??