VIDEO : Neil Patrick Harris Talks About His Relationship With Husband David Burtka

Neil Patrick Harris recently celebrated his 15h anniversary of his first date with husband David Burtka. During an interview with ?Entertainment Tonight,? Harris talked about his relationship. He said: ?I think the secret to a relationship is just perseverance, you know?? According to the Huffington Post, the actor posted a photo of him and Burtka on Instagram. He said he was ?grateful? for his husband, calling him a ?sextuple threat.?