But in an on-stage interview with the women's magazine Brigitte on 26 June, she shocked the German media by saying, in response to an audience member's question, that she had noted other parties' support for gay marriage, and would allow a free vote at an unspecified time in the future.
The day after the Republic of Ireland voted to legalise gay marriage in May 2015, almost every German newspaper splashed a rainbow across its front page.
Nevertheless, she'll go down in history as the chancellor who made it possible.
The bill is one of the very last measures to come through parliament before the September general election.
Civil marriages are legally recognised in Norway, Sweden, Denmark (excluding the Faroe Islands), Finland, Iceland, the Netherlands, Belgium, Spain, Portugal, Luxembourg, France, the UK (except Northern Ireland and Jersey), and the Republic of Ireland.