A tea ceremony is a symbol of purity, stability and fertility.
The purity of the tea signifies the love is pure and noble, the stability of the tea stands for faithful love, and the fertility of the tea means that the new couple will have many children.
The tea ceremony would actually be done right after the couple is married. Though the tea ceremony had evolved from what it had originally symbolised to it being a symbol of the families' welcoming the bride or groom into the family.
Typically in many Chinese wedding traditions, the groom's family takes precedence over the bride's. It's the family welcoming the bride into the family as one of their own, and at the same time, it is an expression of gratitude from teh couple's part.
The couple is basically saying that 'I am marrying into this family, I will show respect by serving tea to the elders'.
