There are a lot of celebrities in the world, and they just can't all be available to stop by the Oscars every year. Those hoping to see an appearance by Michael Fassbender at the 2017 Oscars is one of the many Hollywood A-listers that missed an invitation this year, but Fassbender's second half, Alicia Vikander, is presenting at the ceremony. So that's better than nothing.
Alicia Vikander, who has been dating Fassbender since December 2014, won the Academy Award for Best Supporting Actress for her role in The Danish Girl in 2016. As such, she's returned to present another award, but many an eyebrow rose when Vikander showed up to the Oscars red carpet alone. The couple has previously been very public about their relationship, so it's likely that Fassbender is simply busy working on a film or otherwise occupied in a way that is preventing him from joining Vikander at the ceremony.
Although Fassbender is not at the 2017 Oscars, it's likely that he'll be back sometime in the near future. Fassbender has previously received nominations for his roles in 12 Years A Slave and Steve Jobs, so The Academy clearly have their eyes on Fassbender. If and when Fassbender is nominated again, it's likely he'll attend. It just seems that he was unable to be an audience member in 2017.