My 2 cents..
People get married for different reasons - money, love, sex, wanting children/family, social or professional status, companionship , just to name a few. Sorry.
The reasons people marry does change where the couple is in life. Yes - younger horny people might marry to have XXX-rated sex 24/7, older people might marry for not wanting to die alone.
I am going back on what Imani said about her childhood: MIA father,, mom cold as ice, wanting to be a doctor, and then became pregnant while an intern working crazy hours by someone who went missing ( by his or her choice) on the quick while the child was a toddler.
So in walks into her life Phil. Good guy, who probably has his own laundry list of back-story personal issues -starting with a music career that is-was a has-never been. However , a wonderful prospect to raise the son, so he got the job of "husband". For all we know, sex, with each other might was never part of the deal. I don't think ole Phil was celibate for the last 4-6 years...
Is her book an autobiography? If so - what does it say ?