Just living together does not mean you are considered married.
However, because you do have a romantic/sexual/partnership type relationship, you are also not treated the same as two non-involved individuals sharing accommodation.
Your relationship is, in its bureaucratic significance, less than marriage, but more than just flat-mates.
If it were me, I would ask these questions of the local authorities, particularly
- the Tax Office,
- the Social Security Office, and
- if there are children, also the KESB (Kinder und Erwachsene Schutzbehörde = literally translated: Child and Adult Protection Authority).
This is because, like just about everything else in Switzerland, although federal laws govern the general principle (what counts as a marriage, what does not, and yours is not a marriage) the regulations (who can register what about which aspects their partnership and contracts) can differ from canton to canton, and the application thereof (who might have to pay what to whom) sometimes even from municipality to municipality.
Unmarried partners can be regarded as having responsibilites to each other.
Here, for example, from Basel Stadt http://www.grosserrat.bs.ch/dokument...0000377324.pdf
an explanation that, once an unmarried couple has lived together for five years (and less if there are children), it is considered a stable interdependence, such that in some circumstances the state would not be liable to pay social security because it could be seen as reasonable that one partner (working) would support the other (poor). This document also explains about the tax deductions.
Here, for example, from the City of Zurich: https://www.google.ch/url?sa=t&rct=j...83134100,d.eXY
a checklist-type explanation of the main points of living together as an unmarried couple. See particularly the effects on pensions.