Why didn't India annex Sri Lanka before?

There are the following historical and practical reasons:

First, historical reasons:

1, India and Sri Lanka had different status when they were colonized by Britain. India, Pakistan and Myanmar are all under the jurisdiction of the Indian governor sent by the Queen of England. Due to its superior geographical position, Sri Lanka was directly ruled by the Queen of England, resulting in the situation that the mainland was under the jurisdiction of the Governor and Sri Lanka was directly under the jurisdiction of the Queen of England. So when India became independent, Sri Lanka became independent without joining India.

2. After independence, Sriraka was wooed by India to join India and enjoyed a high degree of autonomy. But Sri Lanka joined the Commonwealth to ensure its own security and is still a member of the Commonwealth. India still has some taboos about Britain, the old sovereign country, and dare not annex it.

Second, the practical reasons:

1, Sriraka is located at the southern tip of the South Asian continent, with superior geographical location, self-sufficiency in natural resources, low dependence on the mainland and weak economic ties.

2. Sri Lanka's foreign policy is non-aligned, and it is closely related to the United States and China. , but also strengthen their own security.