I delighted to speak to Frances Solá-Santiago for Refienery29 to discuss the psychology behind matching couple style. 

“If you think about a brand or a company, they have a way they dress to match their mission, for people who want to monetise their relationship, it makes sense.” 
“One of the main motivations behind dressing a certain way is to fulfil that human desire to belong and to be aligned with a group. When couples come together and form a unit, unconsciously they start to dress alike because it’s an easy way to form that social bond.”
“When you are in a couple, it’s something that you can’t avoid because, as social creatures, we want to establish that bond.”

Go ahead and read the full piece here.