Nepal has a deep relationship with him for keeping Narendra Modi and the Indian state

How did Sikkim become part of India?
A referendum was held in Sikkim to determine the will of the Sikkimese people. It is important to note that at the time of independence Nepali Hindus formed the majority of the population ruled by a Buddhist monarchy. Yet, Sikkim rejected joining the Indian Union, and Prime Minister Jawaharlal Nehru agreed to a special protectorate status for Sikkim. Sikkim came under the suzerainty of India, which controlled its external affairs, defence, diplomacy and communications, but Sikkim otherwise retained administrative autonomy.

At the same time, Sikkim State Congress was founded in 1947 to promote democracy and to end feudalism in Sikkim but its main purpose was to work closely with the Indian National Congress (INC) to successfully achieve the annexation of Sikkim to India. Similarly, Nepal State Congress and Bhutan State Congress were also formed.

Things were going well in the early years after independence as the then king Tashi Namgyal favored closer links with India and advocated land reform and free elections. This allowed various political parties, representing different ethnic groups, to come up. One of them was Sikkim Praja Mandal formed by Kazi Lhendup Dorjee, who went on to become the president of Sikkim State Congress in 1953. Dorjee later met Pandit Nehru in 1954, the Indian Prime Minister promised to give assistance for the progress and economic welfare of the Sikkimese populace and assured Government of India’s support towards political reform in Sikkim.