This is the 4599th most frequent Polish word.
małżeńskim
"Małżeńskim" means "marital" or "pertaining to marriage."
The word "małżeńskie" is used as an adjective describing something related to marriage, in this case, a "marital bed," which typically refers to a bed intended for a married couple.
Właśnie kupiliśmy nowe łóżko małżeńskie.
We just bought a new marital bed.
Here, "małżeńskiej" modifies "poradni" (counseling center), indicating that the services provided are related to marriage or marital issues.
Pani Kowalska pracuje w poradni małżeńskiej.
Mrs. Kowalska works at a marriage counseling center.
In this context, "małżeńskim" is an adjective describing "życiu" (life), showing that the happiness pertains to their married life.