When a couple commits to a long term relationship or marriage, they generally choose to have a family. They do not want to tell their children they met at a bar, but that is precisely the reason many singles go to them. They are less interested in the drinks and entertainment than they are in making a connection, but few of them think of the possibilities in the far future. Meeting at a bar might not be the optimal explanation to tell a child, but it does have the ring of truth to it.
The goal of going to a bar is to meet someone, but few people go home together when they first meet. One of them will often give their phone number or email address to someone who interests them, and they connect at a later time. It is a good way to be sure neither of them are together under the influence of alcohol, and it gives them a way to get out of dating someone if they change their mind.
It is fortunate that not every couple meets at a bar, but it is a reality of single life. Facing the fact that family or friends might never come up with a good match is important, and being proactive in finding a partner is the best way to meet the right one. Instead of being ashamed of meeting a partner that way, couples should be glad they had the opportunity to find each other.
As far as explaining the circumstances to the children, it is best to gloss over reality in many cases. They might think less of their parents, but chances are they will find it unbelievable that their parents were ever cool enough to even get into a bar. It is best to let them have their old-fashioned fantasy that their parents were together forever.