She's been with her boyfriend for over a year and describes herself as a monogamist.
From the dailynews.com
I'm a serial monogamist with serious issues around being in my own company for too long.
From the nzherald.co.nz
You've made quite the swift transformation from misogynist to monogamist.
From the forbes.com
Describing herself as a serial monogamist, she seemed to need companionship with a contract.
From the time.com
So it's not that there is only one, people just stop once they have one, well monogamist do.
From the psychcentral.com
I assume I have been a notably low monogamist all these years.
From the time.com
A serial monogamist, he discovered that little girls don't always grow up in the most delightful way.
From the theatlantic.com
George Clooney is a control freak and a serial monogamist.
From the independent.co.uk
The hit film Philadelphia treats its subject gingerly, making its hero a saint and a near monogamist.
From the time.com
More examples
Someone who practices monogamy (one spouse at a time)
Monogamy usually refers to a form of marriage in which an individual has only one spouse at any one time. However, monogamy may also refer to the more general state of having only one mate at any one time and as such may be applied to the social behavior of all animals. ...
(The Monogamists) The following is a detailed account of each episode plot during the course of the six seasons of Sex and the City.