It’s never right for a marriage counselor to advise someone to get a divorce, just as it would not be right to tell a couple they should get married in the first place. For one thing, it’s against the ethics code of marriage counselors.
To be clear, the therapists hardly ever give direct advice like “you should divorce”. But they make it clear that the marriage is in very bad shape and probably can’t be restored to health, and that it would be unwise or unhealthy to keep trying to salvage it. In other words, there is no realistic alternative to divorce.
So why do some marriage counselors suggest divorce? Sometimes therapists are pessimistic about a marriage because they lack the skills to help. Like doctors recommending amputation because they lack surgical skills to repair a leg.
Other times therapists are pessimistic because they undervalue the importance of lifelong commitment in the face of hard times. They’ve seen a lot of divorces, and maybe are divorced themselves, and don’t see it as something to be avoided if at all possible.
Either way, these therapists can do permanent damage to marriages and families by too strongly influencing a decision with lifetime consequences. And their clients don’t know in advance what they are in for!
But what about dangerous marriages? Yes, it can sometimes be appropriate to recommend a separation if someone is in danger, and legal assistance if someone is being coerced into actions against their interests, but divorce itself is never an emergency. Divorce is a legal process that plays out over time, with many steps along the way, and opportunities to continue discerning whether it is the best way to solve the problems in the marriage.
 AAMFT Ethics Code: 1.8 Client Autonomy in Decision Making.
Marriage and family therapists respect the rights of clients to make decisions and help them to understand the consequences of these decisions. Therapists clearly advise clients that clients have the responsibility to make decisions regarding relationships such as cohabitation, marriage, divorce, separation, reconciliation, custody, and visitation.