Relaxed spouses can be an asset for sure. If one wants to have a relaxed and efficient family life, one person has to be less ambitious.
My experience is almost exactly the same as @hyperJulie 's. My partner did enough to get a degree in college and has been following me every step of the way since. He still works a low-paying job but one that actually stays at work. So when he gets home, he takes care of me, our furbaby, and the house.
I would not be where I am today without him. We graduated college ~6 years ago and I can’t tell you what his GPA was. I can tell you that after early a decade together, 4 years of which we’ve been married, dating him was the best decision I’ve ever made.
Some people are comfortable and appreciative of a less motivated partner, some are not. Many people that I know are in the same occupation, and attracted to those with interests and traits that they have in common. Personally, I’ve never even dated someone outside of high school who wasn’t (or wasn’t going to be) a military pilot. Not even on the radar.
In this case, it sounds like there is an issue with respect. If you don’t respect the other person, the relationship won’t last. People can detect that. As others have said, perhaps the unmotivated person just hasn’t discovered what they want to do yet. These two sound pretty young, so it’s probably best to not make a significant commitment anyways.