What does it mean for boys to release canaries?

It is a symbolic behavior, implying the commitment to love and marriage and the pursuit of freedom and happiness.

At the wedding, the groom will hold a cage with a canary in it. At some point, the cage will be opened to release the canary and let it fly freely. This ceremony symbolizes that the groom is willing to give the bride more freedom, respect her personal rights and choices, and hope that they can pursue happiness and beauty together.