The number eight is considered particularly auspicious in Chinese culture because it sounds similar to the word for 'prosper' or 'wealth'. It is pronounced like "bah" in Mandarin (pinyin: bā).
The visual aspect of the 8th anniversary because it is similar to the infinity symbol which is a happy thing to associate with the connection you have with your husband or wife.
Entering the 8th year is such a blessing. It may not be as grand as the 10th or 25th anniversary but it means that we are getting there. We have surpassed the 7th year itch, as they say. We passed it with flying colors.