Why is this, and what is the male equivalent?
Well, I argue that there is no male equivalent. Men seem to be either in a relationship or single. A 'hoe phase' for a man could be their entire life if they wanted it to be. Whereas for women, their period of sexual promiscuity is contained to just a 'phase', in order to be palatable for men. "Don't worry, she'll be wife material at some point, she's just going through her hoe phase at uni."
For women, there is a separate category besides being in a relationship and being single, and that is The 'Hoe Phase'. Being single doesn't necessarily mean sleeping around, otherwise, we could be labelled as a slag by society. It's different for men. If a man chooses to sleep around when he's single, it is seen as something he 'needs', because of archaic perceptions and outdated stereotypes that men have larger sexual appetites than women. Sleeping around for men is (generally) seen as a given, whereas women are expected to remain chaste and virginal (but also know exactly what they're doing in the bedroom). Of course, some men don't sleep around, but my point is that if they chose to, they wouldn't have as much at stake.
The whole idea around the 'hoe phase' is based on gender, and derives from the Patriarchy, even to the point where women shame other women for it. Slut shaming has been so ingrained into our society, and therefore into our ideas of gender and sexual dynamics, that even women shame other women for having multiple sexual partners, even sometimes without being aware they are doing so. Women are still seen as objects for men to desire but are not granted the privilege to desire men, or show any sort of sexual appetite (this even goes down to the clothes we choose to wear. Showing too much skin? What a slut! Covering up? What a prude!).
The term 'hoe' was first recorded in America in the 1960s, as a shortened derivation of the word 'whore', meaning prostitute. Though these two terms have come to mean different things, it is interesting that the root of the word is derived from a demeaning term used to describe a sex worker. This speaks volumes about the way society, even in the modern-day, views women who have casual sex. Even the word promiscuous has gendered connotations. Have you ever heard a man described using this term?
According to Margaret Atwood, "Even pretending you aren't catering to male fantasies is a male fantasy...You are a woman with a man inside watching a woman. You are your own voyeur". There is some truth in the claim that recently there has been a female reclamation of 'the hoe phase'; a transition from the previous patriarchal and oppressive connotations to something more empowering. But at the same time, are we pretending that we aren't catering towards the male fantasy, and therefore, catering towards the male fantasy? This is where the water muddies slightly, but my point is that taking onus and agency of our bodies and sexual decisions is the first step towards self-empowerment, despite potentially catering towards the male gaze.
In order to combat this idea that all our decisions are predicated on the male voyeur inside our heads, you must have the right intentions behind a 'hoe phase', if you want one. Do it because you want to, not because you want a man to desire you. I know it's sometimes hard to distinguish between the two, but the more we are aware of this, the more we can mentally check that we aren't doing it.