The decline in marriage has been offset by a rise in cohabitation.

同居人数的增加跟结婚人数的减少相抵消。

《柯林斯英汉双解大词典》

Friendship in its usual sense is not tested by the strain of daily, year-long cohabitation.

通常意义上，友谊不会受到日复一日、年复一年的同居生活的压力考验。

youdao

While cohabitation has been on the rise, the overall share of young adults either married or living with an unmarried partner has substantially fallen since 1990.

尽管同居率一直呈上升趋势，但自1990年以来，已婚或与未婚伴侣同居的年轻人的总体比例大幅下降。

youdao

Cohabitation offers people a lot more flexibility and freedom, but that's the downside of it too, looking at it from a more relational -- and particularly from a child's -- perspective."

VOA: special.2011.05.23

Cohabitation can cause legal problems the same way marriage can, particularly if the relationship ends.

FORBES: Prenuptial Agreements for Cohabitants

Cohabitation is bad enough, in Mr Schrameck's view, and Mr Chirac has made it worse.

ECONOMIST: French politics

Cohabitation, in the cases where assets need to be protected, is more than just having a roommate.

FORBES: Prenuptial Agreements for Cohabitants