How would you feel if you'd missed out on sleeping with your first love? would you want to find them after 40 years?

Missed something: Would depend upon present circumstances. Would contact first love if i was free to resume the relationship. Would not if i was in a committed relationship which would be damaged by renewing with your first love. You should first weigh all the pros & cons. Of course your first love is likely not free or want to renew the old relationship. Think it over carefully.