According to the OP2 guide from CIC found here:
http://www.cic.gc.ca/english/resources/manuals/op/op02-eng.pdf5.46.
Can conjugal partners be substitutes for fiancé(e)s?
Conjugal partners are NOT substitutes for fiancé(e)s. CIC decided that it no longer wanted to be
in the business of assessing future relationships or the intention of two individuals to establish and
maintain a conjugal relationship. Thus, there is no fiancé(e) category in the IRPA and Regulations.
If they intend to apply as spouses, Canadians and their foreign national fiancé(e)s are expected
to be married before the immigration process takes place, i.e., the foreign national must be
married to the Canadian sponsor and apply to immigrate as a married spouse.
Fiancé(e)s are individuals who intend to marry and intend to establish a conjugal relationship. In
most cases, they have not yet established a conjugal relationship. They intend to combine their
affairs and become mutually interdependent, but have not yet done so. Even if they have a sexual
relationship, they have not yet achieved the level of mutual interdependence that characterizes a
conjugal relationship although they intend to do so at some point when they marry.
Most traditional fiancé(e)s cannot meet the definition of conjugal partner. They have not merged
their affairs and established the required mutual interdependency. As well, conjugal partners must
have established a sexual relationship, and traditional fiancé(e)s would be unlikely to meet this
criterion