Yes, i have known someone who was in an unhealthy relationship. If the relationship is abusive then it is unhealthy, or if you don't take each other seriously or don't care for the other person, you don't trust them, constantly put them down or make them feel insecure, if you two fight constantly, blaming the other person, are not open with them on many things, not communicating often or at all, trying to control the other person or feel controlled, keeping secrets from them, not respecting them or their personal space (physical and emotional), unhealthy jealousy, not being able to compromise, and not being on the same level of how much you care for each other. this can be good for romantic or non romantic relationships.
