Let me first discern settling from compromising. Compromising is understanding my partner is a real human with flaws, and meeting halfway with imperfection while still appreciating them as the full package. Settling is committing to someone who I perceive to be lower than myself, lower than someone I normally date, and/or lower than someone I normally would want.

Settling is, at its worst, emotional infidelity if you are always comparing your partner. Settling, at minimum, is transactional.

It is selfish behavior, that typically leans on finding security, stability, for oneself with the illusion of a romantic love. To me, deeper love requires respect, and you don't respect your partner if you see them as inferior or "good enough."

Settling also typically relies on the other person's ignorance, in which case, involves a lifetime of lying which I would consider immoral itself. You're taking away another person's ability to choose for themself to be with a mutual kind of love.

Beyond the obvious abuse and violence, settling is one of the worst things you can do to someone you're committed to.