Have you got any particular shows in mind? I've been rewatching Gilmore Girls lately, which basically ran on the female leads having multiple love interests, although there were several instances where those male love interests were partnered with other people and experience the kind of romantic conflict you describe. But I agree that it's much rarer to see a one guy-two girl love triangle.

This is definitely a thing, but I think it's not so much about female characters 'getting away' with more as it is really strong lingering ideas about femininity and masculinity.

I think it's perceived as attractive (to the audience, not sexually per se) for a man to be strong and decisive. Therefore, a storyline where a male character is torn between two or more female love interests risks making him seem silly, weak or frivolous in the eyes of the viewer at home.

Whereas, an audience will more readily accept a female character being torn between multiple men, as there is a greater tolerance/expectation for women to be indecisive, emotional etc.

EDIT: also, and this is going back in history but I think the effects still linger, back in the day a woman's choice of husband generally had a more significant impact on her future life than a man's choice of wife. Perhaps that accounts for the long-standing popularity of storylines where female character must decide between multiple suitors.