Couples therapist reveals the one thing you should never do in a relationship

A couple's therapist who has been married to her husband for 22 years has shared the one thing you should never do in a relationship.

Sinead Smyth, who practices in California in the US at East Bay Relationship centre, says the key to a successful relation is to pause before speaking during arguments.

"In the heat of an argument, it's not going to come out well," she told Today.com. "So I usually check myself, give myself three seconds."

She warns couples not to "fire off when you're in conflict."

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"Take a break, even if it's just a few seconds, and make a decision about whether it should be said or not and how you're going to say it," she advises others.

She says while it is normal for couples to occasionally disagree, it is how they navigate those disagreements that is key.

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Smyth also suggests couples not avoid conflict, explaining she and her husband turn "toward" each other during these times and focus on "connection."

She also encourages couples to do small, kind things for each other rather than larger ones.

"That would be my takeaway is that it's about doing certain small, low-level things consistently," she explained.

Weekly dates are another key to here marital happiness.

"We're just really trying to stay with who the person is as a person rather than the logistics and chores and tasks," she added.