Why doesn't my wife prioritise sex as much as I do?

We have been married for just an year and a half and we don't have kids yet nor are we planning any at the moment. But it already seems like that her interest in me sexually is on the decline. We talk, have our meals together, go out, she loves to cuddle and kiss but never ever initiates sex and if I do it she either does it half heartedly or avoids it completely. Domestic chores are much of a priority for her than intimate time with me. We don't fight much, she is one of those persons who stay away from confrontations and stuff. But this is really annoying me… Like last night, we were cuddling and she feel asleep on my chest before I could initiate anything. She hugs and holds me but hardly wants to go beyond that. In the last three weeks, we have done it just three times.

Another thing is that she has this urge to keep the house in perfect shape so she cleans every nook and corner of the house, does the laundry, dishes, cooks. I mean I offer to help but she always says that she wants to do it on her own! Now by bedtime she is tired as hell and goes to bed early and falls asleep within seconds.
But then again why is she not prioritising "us time " over the chores or other things. I love her and want to work through this. Help '?

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