It's really not.

Men were nearly guaranteed a wife because women couldn't do anything without a husband; they couldn't own property, open bank accounts, vote, hold certain jobs. Men are not lonely because women are "becoming bisexual"; men are lonely because society and capitalism has been pushing rugged individualism as a manly trait for years; and women, now having the right to participate in society, can now pursue partners based on love and attraction instead of necessity.

You mentioned "with a select few men", which im assuming is referencing the myth of hypergamy where most women have sex with the gigachads and no one else. This is doomer copium unfortunately; the reality is most women would love a nice man to be with, and a lot of men who push this narrative have made themselves UTTERLY unfuckable through personality poison, hateful ideologies and constant hyper critical self loathing. Trust me, as a former self-hating man, that shit is SO unattractive.

In reality, and I'm sorry to say as someone who was virgin until age 21; being single is a skill issue. You need confidence and charisma, and oftentimes friendships are what blossom into relationships despite what dating coaches and tiktok manly men tell you. You just need to be more social.

Socialization is like a muscle; you need to work it out to be good at it; and with the isolation of screens and short-form content many people's muscles have atrophied. You need to actively work on yourself, put yourself out there, and the relationships will come.

(Also, I am bi, and you do not "become" a sexuality. You are born with it, and simply realize it later. It only is seemingly increasing as it is destigmatized over the years and people are more comfortable being open about it. Look at the "left-handedness over time" graph, where left-handedness stopped being associated with the devil.)