Yo Kass answered
A) He is very disorganised.
B) He's just not that into you.
Why your boyfriend keeps cancelling your dates
If your boyfriend keeps bailing on you, I think you're totally right to be at least a little skeptical about his commitment to the relationship.
A good boyfriend will want to spend as much time as possible with you. If he's besotted with you, then every moment apart will cause him anguish.
My advice would be to voice your feelings in a calm and clear way. Make sure he understands you're worried about his perceived lack of enthusiasm, but try to do it in a way that doesn't make you seem needy or fussy.
Basically - you're within your rights to expect him to keep his promises and show up to dates, but just make sure that he doesn't have a valid excuse before you put the heat on him!