The motto “live and let live” sounds great in theory, but many people find it difficult to carry out in practice. Instead, people tend to think that their own lifestyle is totally awesome and that other people should make the same decisions that they have made.
Relationship decisions in particular can be an easy target for judgment. For example, you may know a single person who derides their friends for pairing up, questioning why anyone would choose to shackle themselves to one partner rather than “live it up” with the single life. Or you may know that smug married couple who pushes for other couples to also tie the knot, so they can similarly bask in wedded bliss.