Mia moglie preferisce lavare subito i piatti, mentre io finisco per riordinare il salotto.

In Italian, with most singular family members, the definite article is usually not used before a possessive adjective.

So you say:

• mia moglie = my wife
• mio marito = my husband
• mio padre = my father

But with plural family members, you normally do use the article:

• i miei genitori = my parents
• le mie sorelle = my sisters

There are also some exceptions, especially with modified family nouns or affectionate forms, but in a basic sentence like this, mia moglie is exactly what you expect.

Preferisce is the third-person singular present tense of preferire.

The subject is mia moglie, which is she, so the verb has to match:

• io preferisco = I prefer
• tu preferisci = you prefer
• lui/lei preferisce = he/she prefers

So:

• Mia moglie preferisce... = My wife prefers...

Also, preferire is one of those Italian verbs that often inserts -isc- in some present-tense forms, like:

• preferisco
• preferisci
• preferisce
• preferiscono

After verbs like preferire, Italian usually uses the infinitive when the same person does both actions.

So:

• Mia moglie preferisce lavare i piatti literally means
• My wife prefers to wash the dishes

This is very similar to English:

• She prefers to wash
• She likes to read
• I want to leave

In Italian:

• preferire + infinitive
• volere + infinitive
• dovere + infinitive

So lavare stays in the infinitive because it depends on preferisce.

Subito means immediately, right away, or at once.

In this sentence:

• lavare subito i piatti

it means she prefers to wash the dishes right away.

Its position is natural because adverbs in Italian are often flexible, especially with infinitives. You could also hear:

• preferisce subito lavare i piatti
• preferisce lavare i piatti subito

But lavare subito i piatti sounds very natural and clearly connects subito with the action of washing.

Italian usually uses the definite article more often than English.

So where English often says:

• wash dishes

Italian commonly says:

• lavare i piatti

Literally, that is to wash the plates/dishes, but idiomatically it just means to do the dishes or wash the dishes.

This is very normal in Italian with everyday objects and general categories:

• Mi lavo le mani = I wash my hands
• Chiudi la porta = Close the door
• Leggo il giornale = I read the newspaper

Yes, mentre usually means while, but in sentences like this it can also have a contrastive sense, similar to whereas or while, on the other hand.

So:

• Mia moglie preferisce lavare subito i piatti, mentre io...

means something like:

• My wife prefers to wash the dishes right away, whereas I...

It is not only about two actions happening at the same time. It also highlights a difference in habits or tendencies between the two people.

That is true: Italian often leaves out subject pronouns because the verb ending already shows who is doing the action.

So you could say:

• ..., mentre finisco per riordinare il salotto.

and it would still be correct.

But io is included here for contrast:

• my wife does one thing,
• I, on the other hand, end up doing something else.

So io is there for emphasis, not because it is grammatically required.

Finire per + infinitive is a very common Italian structure meaning:

• to end up doing something
• to wind up doing something

So:

• finisco per riordinare il salotto means
• I end up tidying the living room

It often suggests that this was not necessarily the original intention, but it is what happens in the end.

Other examples:

• Ha finito per accettare = He ended up accepting
• Abbiamo finito per ridere = We ended up laughing

Riordinare means to tidy up, put back in order, or straighten up again.

The prefix ri- often gives the idea of:

• again
• back
• restoration

So:

• ordinare = to arrange / put in order
• riordinare = to tidy up / restore order

In a house context, riordinare il salotto is very natural for tidying up the living room.

Salotto means living room or sitting room.

The article il is used because Italian normally includes the article with rooms and many nouns in general:

• il salotto = the living room
• la cucina = the kitchen
• il bagno = the bathroom

Also, just like with i piatti, Italian often uses the definite article where English may sound a bit more general.

So riordinare il salotto is the normal way to say tidy up the living room.

Not exactly, though in some contexts they can overlap.

• lavare i piatti = to wash the dishes
• fare i piatti can also be used in everyday speech to mean do the dishes, but it is less universally standard than lavare i piatti

If you want the clearest, safest phrase as a learner, use:

• lavare i piatti

That directly expresses the washing action.

It can naturally suggest a habit or a typical pattern, especially because of the present tense.

• Mia moglie preferisce... mentre io finisco per...

This sounds like:

• My wife tends to prefer... while I tend to end up...

Italian present tense often covers both:

1. a general fact or habit
2. something happening now, depending on context

Without extra context, many learners would read this sentence as describing a usual division of tasks or a recurring situation.

You could say ma, but it would slightly change the feel.

• ..., ma io finisco per riordinare il salotto = ..., but I end up tidying the living room
• ..., mentre io finisco per riordinare il salotto = ..., whereas I end up tidying the living room

Ma gives a more direct but contrast. Mentre feels a bit smoother and often sets up a side-by-side comparison.

In this sentence, mentre works very well because it compares her preferred task with what I usually end up doing.