Birthdays happen every year and everybody has them, however some parties are bigger deals than others.  If more planning and resources have gone into a party than usual, it’s a safe bet that this would be a big deal to miss.  Milestone Birthdays, like anniversaries, are often of greater significance.  If there is a card with the number on it in the grocery store, then it is a milestone. 50, 60, 75, 95, 100 – these are the biggest usually, but any multiple of 5 can be a big one.  Missing her grandpa’s 73rd Birthday dinner is likely a more forgivable offence than skipping out on her great grandmother’s 100th Birthday bash or her dad’s 50th.
Anything that is specific to your partner trumps all:  Her birthday.  Your anniversary.  Her graduation.  This should go without saying.

There is a very good chance that to her, sporting events are all created equal.  Since there is always some sporting event happening, what’s the big deal with missing one?  Catch the next one.  Obviously, some clarification is needed in this field.  If you want her to differentiate between sporting events, then you’ll have to as well.  To show her the difference between a normal game and the World Cup, the Super Bowl, or any playoffs, you’ll have to display your willingness to miss normal games, but talk up your excitement at playoff time.  Pick your battles and she’ll come to recognize the big things.

Always Personalize
Different things are important to different people.  It is impossible to know exactly how important something is to your partner without talking about it.  It is a good idea to discuss common events to get an idea of where things stand with her. Birthdays, anniversaries, and holidays: from Valentine’s Day and Halloween to faith holidays and family traditions.  Getting a general idea of each other’s expectations before an actual event comes into question will help you to avoid conflict and possible disappointments.

Company Does NOT Love Misery
It is far better to hash things out in private than to bring them with you when you go out.  Nobody wins when you attend an event and people (like your partner) can tell that you don’t want to be there.  If you really, really don’t want to go – it is better to tell her than for her to find out by your behaviour at her cousin’s birthday party. 

Your willingness to show up isn’t worth anything if you don’t make a decent social effort. Feeling awkward is one thing, and she will expect that in certain social circumstances, but acting miserable is quite different.  And you will definitely pay for it later.  This is not a time when a partial effort will earn you part marks, and it may even leave you worse off than flat out refusal if you’ve embarrassed her by your behaviour in front of others.

Advice to the Ladies
The image that my suggestions may have painted is one of a matriarchal social scene.  This is only because women are the infamous keepers of couple’s social calendars.  All of this advice should go both ways though. Respect important events.  Be clear about expectations and learn what his are.  Be happy at his buddy’s Super Bowl party and at his mother’s Sunday dinners, or stay at home.

Relationships are full of compromise and just like it takes two to tango, to form a relationship, and to have a conversation, it also takes two people’s input to properly negotiate a couple’s calendar.