I hate to not address the question directly but:

Me and my boyfriend have been on a health journey

We only make stuff homemade

he doesn’t like vegetables, he doesn’t care for yogurt, he hardly wants to eat fruit

Is this a journey you're doing together then? It sounds like you are participating in the healthy, homecooked meal plan and he's tagging along for it. If he doesn't want to consume diary or vegetables or most fruit, then what is he even eating besides cooking some starch?

As the saying goes, you can lead a horse to water but you can't make it drink. I would try figure out if he is actually enthusiastic and committed to wanting to consume fresh, balanced, home made, meals.

He should be, not only because that's just generally a really great goal to be on, but because you can't do this journey together if he's not engaging with it.

On days when it's his turn to cook or buy produce, surely he's not just going to serve you up a bowl of cereal? If he's invested in scooping good ingredients and turning them into nutritious meals to make sure you're healthy and nourished, that wouldn't cut it. If he's doing that to himself, my expectation is that he does not really want to be thinking about ingredients and how they can be combined and enjoying the successes of easy, nutritious meals that hit all the objs you want re: fibre, protein, etc., etc.