Happy Cinco de Mayo! Which brings me to the question...
Do you have cultural events mingling with the events of your novel? I'm not suggesting your plot should be centered around cultural traditions, but that you consider using events (real or imagined) in the finer details that follow your existing plot.
Cultural events are the world-building results of a society. They add a sense of depth and realism for the reader, and the reader might even gain a new appreciation for something they didn't know (if your events are accurate). They can reveal a character's personality and upbringing, and the level of tolerance, understanding, and maturity of sidekick characters. They map the passage of time, season, and weather. They create a calendar deadline that can't be changed, even if your mc hasn't finished saving the world.
They can also instigate conflict and moral dilemmas. Would your mc pick a family tradition/gathering over a first-year anniversary? Does the significant other respect that decision? And on that note, did the mc even warn his date that there might be an issue when he brings her to a family event for the first time? Did he explain the expected customs so she could be prepared?
While your mc is actively saving the world, would his/her mother call to remind him/her that it's Mother's Day, and that a phone call would have been appreciated?
Does an unusual attempt at meal preparation reveal the fact that the in-laws are coming for Memorial Day weekend, and one spouse neglected to tell the other?
Does your mc care if the family doesn't approve of his/her friend for racial or religious reasons? It'd be kind of sad if the mc was just rebelling the family standards, and didn't take the long-term effects into consideration because the relationship wasn't supposed to last. (Character growth!)
Does your mc buy decorations/gifts at the dollar store the day of... or have they been prepping all year? Oh the stress if all that work was suddenly lost. How will they handle the holiday without the "things"... How would they handle a holiday they love in a society where that holiday isn't recognized?
Cultural events and holidays happen in all societies, no matter how much stress your character is trying to handle at the time. Don't let your plot get off track, but don't forget the calendar!