"Kim has work and projects that are important to her, and Kanye has his," the source tells PEOPLE. "Their lives don't overlap much." (A rep for Kardashian West, 40, had no comment when reached by PEOPLE, and a rep for West, 43, did not respond to PEOPLE's request for comment.)
Still, the source says "Kim seems happy" and is "very focused on work and causes."
"She strongly believes she can make a change when it comes to prison reform," the source says of the star, who is studying to become a lawyer and this week publicly pushed for President Donald Trump to commute the sentence of Brandon Bernard. Bernard, who was convicted of murder as a teenager in 2000, was executed by the federal government on Thursday.
"This is her passion," the source says of Kardashian West's justice reform advocacy. "Her family is very proud of her."
West, meanwhile, has maintained a relatively low profile in recent weeks after thrusting himself into the spotlight this summer.
In July, he launched a controversial bid for president of the United States and divulged deeply personal details about his family and marriage on the campaign trail and on Twitter. Sources told PEOPLE at the time that West's campaign, which had multiple Republican ties, came amid a new cycle in his bipolar disorder.
It also landed his marriage in crisis, and West and Kardashian West appeared to be on the brink of divorce before reconnecting in August and spending private time together with their children. (They two share daughters North, 7, and Chicago, 3 in January, as well as sons Saint, 5, and Psalm, 18 months.)
"She just wants to do what's best for the kids," a source told PEOPLE at the time.
Kardashian West — who in July publicly addressed her husband's bipolar disorder diagnosis in a lengthy statement on social media, asking fans for "compassion" — most recently posted about their relationship in a Nov. 22 Instagram post.
"Happy 10 year anniversary to Kanye's 'My Beautiful Dark Twisted Fantasy' album," she wrote, referencing the rapper's hit 2010 album. "For those that don't know the story behind 'Lost In The World'...Kanye couldn't come up with some of the lyrics but then realized he had them in a poem he had written me that was my birthday card he gave me for my 30th birthday."
"He took the poem he wrote me and made it the song," she continued. "I keep everything! Swipe to see the card."