Vichitravirya's death is described in this chapter of the Adi Parva of the Mahabharata:
And though Vichitravirya was virtuous and abstemious, yet, proud of youth and beauty, he soon became lustful after his marriage. And both Ambika and Ambalika were of tall stature, and of the complexion of molten gold. And their heads were covered with black curly hair, and their finger-nails were high and red; their hips were fat and round, and their breasts full and deep. And endued with every auspicious mark, the amiable young ladies considered themselves to be wedded to a husband who was every way worthy of themselves, and extremely loved and respected Vichitravirya. And Vichitravirya also, endued with the prowess of the celestials and the beauty of the twin Aswins, could steal the heart of any beautiful woman. And the prince passed seven years uninterruptedly in the company of his wives. He was attacked while yet in the prime of youth, with phthisis. Friends and relatives in consultation with one another tried to effect a cure. But in spite of all efforts, the Kuru prince died, setting like the evening sun. The virtuous Bhishma then became plunged into anxiety and grief, and in consultation with Satyavati caused the obsequial rites of the deceased to be performed by learned priests and the several of the Kuru race.
Phthisis is another word for pulmonary tuberculosis. Here's the original Sanskrit verse if you're interested:
tābhyāṃ saha samāḥ sapta viharan pṛthivīpatiḥ
vicitravīryas taruṇo yakṣmāṇaṃ samapadyata
Yakshma is the Sanskrit word for tuberculosis. In any case, the Mahabharata passage suggests that Vichitravirya's death was ultimately caused by his overindulgence in amorous pursuits. You see, Ayurveda utilizes the theory of bodily humors or Doshas, and associates tuberculosis with a specific imbalance of those Doshas which can be caused by an over-indulgence in amorous pursuits. (In the Greek theory of humors, this would be classified as an excess of blood, but the Ayurvedic theory is more complicated, and it may be an excess of one of the Kapha Doshas as described in this book.)