The calm lake seldom betrays its roiled depths. The Tiger/Cancer type is a person of vast unrest. Your seething torment is completely internalized, however, as befits your Crab half. The ego-tripping of the Tiger can, in a Cancerous environment of isolation and self-obsessed withdrawal, be brought to almost pathological levels if not tempered now and then with a dose of reality. This is why you have that material side that you're always indulging -- and why you should continue to pamper yourself every now and then with some of the finer things in life.
These luxuries are your necessities. You need them to get you out of yourself once in a while. If your mate can't understand this, too bad for them, but don't let their quest for an explanation of the causes of your wild mood swings cast you into the depths of an abiding sulk. You're better than that, and besides, your internal chaos can produce sublime beauty in the arts if allowed the proper concentration and discipline.