Good suggestion, Errol. Several people have complained of the same thing - the inability to show an unmarried couple who had children together as connected in the data section.
Making it show as a marriage only if a marriage date is present won't work, though - in many cases, we know two people were married but don't have date or place information about the marriage. I would like to see an extra field, much like the certainty fields we have for dates and places, where we would could characterize the relationship by selecting married, partners, other, (more options???)