Blase suggests you're too accustomed to something to find it interesting or exciting anymore. He was blase about his birthday, having had extravagant parties every year.
Pro Tip 2/3
Hidden Disappointment
Being blase can mask a deeper disappointment at losing the ability to enjoy something. Even the fireworks left her feeling blase, much to her own dismay.
Pro Tip 3/3
Not Negative
'Blase' doesn't convey anger or sadness, just a lack of enthusiasm. Despite the crowd's cheers, the champion appeared oddly blase.