There could be various reasons. Maybe it's a matter of a new piece of furniture or a tight space in the house. For example, if you got a small car recently and he's a big guy, he won't fit in it comfortably. Or perhaps you bought a new piece of clothing for him that was the wrong size and he won't fit into it.
First, you need to figure out exactly what he won't fit into. If it's a physical space like a small closet, you could consider reorganizing or expanding it. If it's a social situation, encourage him to be himself and find his own niche within the group.
It could mean that in a physical space or a piece of clothing, your husband is too large to fit. For example, if you bought a small tent for a camping trip and your husband is a big guy, he literally won't fit in it. Or if you got him a suit that was mis - sized, he wouldn't fit into it.
Another possibility is in a relationship dynamic within the real story. It could be that the husband and the wife have different goals or lifestyles now. For instance, the wife has become very fitness - oriented and is always on the go, while the husband is more of a homebody. So in the context of her new active lifestyle, he won't fit in as he doesn't share the same interests or energy level.
Imagine a story where a couple moves to a new city that is very artsy and cultural. The wife quickly gets involved in local art galleries, theater groups and cultural events. But the husband is more into sports and has no interest in the arts. He feels out of place and doesn't engage with the new community in the same way as the wife. So in this real - life situation of their new city life, the husband won't fit.
Well, when you say your husband doesn't fit the story, it might suggest that his role or contributions don't fit the overall plot or theme you had imagined. Could be his actions are out of sync with the story's direction or his personality clashes with the story's tone.