Which factor is responsible for increasing the feeling of alienation among the Sri Lankan Tamil's?

Sri Lanka is an island nation, south of India. It got independence in 1948. It has a diverse population like most of the South Asian nations.

The population in the majority is Sinhala speakers, which account for about 74% of the total population and rest are Tamil Speakers.

When Sri Lanka recognized Sinhala as the only official language it disregarded Tamils. They felt that they were denied equality. As a result, the relationship between the Sinhala and the Tamils strained and the Sri Lankan Tamils launched movements against the government.