Your birthday has come and gone. You had a great time, except for one thing -- the person you're dating didn't join you in celebrating. In fact, he seemed so oblivious to the occasion that you're wondering if he intentionally "forgot." While disappointing, there are several reasons this could happen, not all of them bad. Open the lines of communication and get to the bottom of his birthday aloofness to pave the way for better celebrations later on.

A Lack of Funds

Expectations for birthday celebrations in our culture are high. The person you're dating may have felt pressured to spring for dinner, splurge on an expensive gift or come over bearing balloons and flowers. If she's broke, the whole affair may have seemed overwhelming, making it seem like a better option to ignore your birthday instead of having to explain her low bank balance. Being broke can be what behavioral scientist Christie Hartman refers to as an "Achilles heel" in dating. The resulting lack of confidence in herself because of this perceived flaw may have resulted in the bad behavior of ignoring your birthday. If you suspect this is the case, let her know that it's truly the thought that counts.

Head in the Clouds

Some people tend to mentally float above the rest of the world, blissfully going about their daily life without worrying about mundane details like dates and deadlines. If this describe the person you are dating, chances are, he didn't intentionally ignore your birthday -- it just didn't make it onto his radar screen. People with this tendency, for example, those with ADHD, can compensate for their forgetfulness by programming reminders for important dates in their cell phones, notes therapist Allan Schwartz in an article for Pecan Valley Centers for Behavioral and Developmental Health Care. However, your sweetheart may not be at that level of self-awareness yet. Either find a way to make sure he remembers, or be prepared to let it go.

Unexpressed Anger

When people feel angry and don't know how to express it properly, they often resort to passive-aggressive behavior. This can take the form of "intentional mistakes" and procrastination, according to the Mayo Clinic. If the person you are dating is harboring resentment over something that happened between you in the past, "forgetting" your birthday may be her way of expressing her displeasure. If you suspect anger is lurking in the background, it's time for a heart to heart to uproot it and address the issue.

Family Background

Birthday celebrations are one of the types of family traditions that most embed themselves in our memories, says Valley Forge Christian College president Don Meyer in a "Huffington Post" article. If the person you're dating grew up in a family where birthdays were given only faint recognition, if any at all, he's unlikely to pay attention to your birthday, either. Talk to him about what his birthdays were like growing up, and you may gain some insight into his recent neglectful birthday behavior.