Unlike the mentioned examples of birthday celebrations, the Bible does not put marriage in a bad light. Jesus himself both attended a marriage celebration and contributed to the pleasure of the occasion.—John 2:1-11.
Notice what the 10/15/98 Watchtower says concerning this:
"It thus would not be strange that a couple might on their wedding anniversary take time to reflect on the joyfulness of that event and on their resolve to work for success as a couple. Whether they focus on this happy occasion in private, just as a couple, or they have a few relatives or close friends with them would be for them to decide. The occasion should not become a mere excuse for a large social gathering. On this occasion Christians would want to be guided by the principles that apply every day of their lives. So whether one takes note of a wedding anniversary or not is a personal matter. - Romans 13:13, 14."
For more, see:
Why Don't Jehovah's Witnesses Celebrate Birthdays? (Defend Jehovah's Witnesses)
WEDDINGS - Links to Information (INDEX; Watchtower Online Library)
RING (Insight-2 p. 812; Watchtower Online Library)
Should WEDDING RINGS and the use of days and months of the GREGORIAN CALENDAR be avoided by true Christians? (Search For Bible Truths)
A wedding ring has no direct relationship to any act of worship... (Jehovah's Witnesses Questions and Answers)
No pagan worship can be found in the history of the wedding ring. (Cyclopaedia Quotes from 1972 Watchtower article, p. 63 (Jehovah's Witnesses Questions and Answers)