Depending on the visa category and your partner’s immigration status in the UK, you may be eligible to apply as an unmarried partner or fiancé.
If your partner is a British citizen or settled in the UK, you can apply as fiancé or proposed civil partner, which will facilitate entry to the UK to marry or enter into a civil partnership. Once in a legal relationship, as issued by UK authorities, you can further apply to remain long-term as the spouse or civil partner of a British citizen or settled person in the UK.
If your partner is a British citizen, settled in the UK or applying for a UK visa, including work and study visas, and you have been living together for at least 2 years, you can qualify as an unmarried partner. Partners who have been living together for at least 2 years in a relationship akin to a marriage are eligible for the same visas as a couple in a legal marriage or civil partnership.