How could this be the case regarding changes in love?

Love makes people stupid .

Researchers at Leiden University in the Netherlands found that people in a romantic relationship have poorer attention and thinking abilities, and score lower in both text memory and numerical calculation. This is because people use a large part of their cognitive resources to think about their loved ones.

Love can be overstimulating.

Neuroscientists at the Albert Einstein College of Medicine performed MRI scans of the brains of people in love and found that the same neural system associated with cocaine addiction became active in their brains, which mainly manifested as being easily overexcited, talkative, and like to sing.

Love can slow people down.

Researchers found that men in love will adjust their walking speed to match their partner's pace. This strange phenomenon does not occur when they are with the same sex.

Love can alleviate people's pain.

Psychologists at Stony Brook University in New York have discovered that some of the same brain areas activated by intense feelings of love are the same areas where painkillers work. In fact, just holding your loved one's hands can have a pain-relieving effect.