The rules are quite clear and you need to have been living together as a married couple for 2 years and she must be on a dependant visa at the time you apply for ILR (the rules do not state that she must have been on a dependant visa for the 2 years). See below
319E. Requirements for indefinite leave to remain
To qualify for indefinite leave to remain as the Partner of a Relevant Points Based System Migrant, an applicant must meet the requirements listed below. If the applicant meets these requirements, indefinite leave to remain will be granted. If the applicant does not meet these requirements, the application will be refused.
(a) The applicant must not fall for refusal under the general grounds for refusal, and must not be an illegal entrant.
(b) The applicant must be the spouse or civil partner, unmarried or same-sex partner of a person who is, at the same time, being granted indefinite leave to remain as a Relevant Points Based System Migrant .
(c) The applicant must have, or have last been granted, leave as the Partner of the Relevant Points Based System Migrant who is being granted indefinite leave to remain.
(d) The applicant and the Relevant Points Based System Migrant must have been living together in the UK in marriage or civil partnership, or in a relationship similar to marriage or civil partnership, for a period of at least 2 years.
(e) The marriage or civil partnership, or relationship similar to marriage or civil partnership, must be subsisting at the time the application is made.
(f) The applicant and the Relevant Points Based System Migrant must intend to live permanently with the other as their spouse or civil partner, unmarried or same-sex partner.
(g) The applicant must have sufficient knowledge of the English language and sufficient knowledge about life in the United Kingdom, with reference to paragraphs 33B to 33F of these Rules, unless the applicant is aged 65 or over at the time this application is made; and
(h) The applicant does not have one or more unspent convictions within the meaning of the Rehabilitation of Offenders Act 1974.
If she is under 180 days, it should be fine but you should submit proof why she has been away e.g. mat leave etc
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