I would place this one in the 50s. During the late 40s and early 50s, it was very fashionable to use curtains - rather than doors - to separate rooms. Doesn’t look like an arched doorway - but it COULD be. During that time period, you also usually did not find many cupboards with doors on them. Rather, you had curtains over the cupboards. The same was true of the area under the sinks - both kitchen sinks and bathroom sinks. You didn’t enclose the area under a sink with a cabinet which had a door to close. Instead, you had a little curtain which closed off those areas under the sinks - and hid the plumbing under the sink from view . Since one of the recommendations which people make for preventing pipes from freezing in the winter is to open up the doors under the sinks - it was probably practical on a number of levels to have under-sink pipes which were hidden by a curtain rather than by an enclosed cabinet.
I would place this one in the 50s. During the late 40s and early 50s, it was very fashionable to use curtains - rather than doors - to separate rooms. Doesn’t look like an arched doorway - but it COULD be. During that time period, you also usually did not find many cupboards with doors on them. Rather, you had curtains over the cupboards. The same was true of the area under the sinks - both kitchen sinks and bathroom sinks. You didn’t enclose the area under a sink with a cabinet which had a door to close. Instead, you had a little curtain which closed off those areas under the sinks - and hid the plumbing under the sink from view . Since one of the recommendations which people make for preventing pipes from freezing in the winter is to open up the doors under the sinks - it was probably practical on a number of levels to have under-sink pipes which were hidden by a curtain rather than by an enclosed cabinet.