It should say a little of how he feels about them to consider her Mrs. Winchester even though its said in the moment. It should indicate that he sees them long term where it matters (because he does). Sam Winchester never has dated around more than he has needed to. He knew she was his girl from the moment he first set eyes on her to now. Her hum transfers a sense of contentment, her fingers make the hairs on his arm stand on end and skin tingle underneath while the shock sparks life every want and need to tilt her bring himself to kiss her fiercely. Little things like when her eyes go black or the light flickers make his heart rush more. They're quite the unusual pair but they fit together.