A lot of us who are anti-unicorn hunters started out as unicorn hunters ourselves and have learned that it's not the best approach to relationships. You can't magically go out and find someone who will seamlessly fit into your (the couple's) life. When I comment it comes from a place of learn from my mistakes and save yourself a lot of heartache.
What I object to is the view that the unicorn in question is some kind of victim if she does get involved with a couple. We're assuming everyone involved are competent adults making decisions for themselves. If they are all going into something that's going to end in an epic shit show they are all equally to blame. I don't think we need to shield potential unicorns from the evil unicorn hunters.
Everything will be ok in the end. If it's not ok it's not the end.