The literal translation for the phrase I want to be with you is Io voglio essere con te but it is more common for Italians to say Io voglio stare con te (literally: I want to stay with you) instead. It is made up of the following components:
Io (I) + voglio (first person present indicative of volere ‘to want‘) + stare (infinitive of ‘to stay‘) + con (with) + te (you).
Note that the subject pronoun io ( I ) can be omitted because the ending of the verb (in this case voglio) already identifies the subject. However subject pronouns are used for emphasis, or to distinguish one subject from another, as in the following phrase:
Io voglio stare con te ma tu non vuoi stare con me.
I want to be with you but you don’t want to be with me.
This phrase may refer to a short period of time (e.g. Voglio stare con te stasera = I want to stay with you tonight) or to an extended period (e.g. Voglio stare con te per sempre = I want to stay/be with you forever).
Italians often use stare to refer to a romantic relationship between two people.
Marco sta con Laura adesso.
Marco is with Laura now.
(Marco is in a relationship with Laura now)
You can also use stare to say that you’re living with someone. For example:
Marco sta ancora con i suoi genitori.
Marco still lives with his parents.
Then we have voglio rimanere con te which means I want to stay / remain with you. It has a very similar meaning, but it implies you’re already with that person and want to continue to be with him or her.
Voglio rimanere con te.
I want to stay with you.
(I want to continue being with you.)
You can also say Voglio vivere con te which means I want to live with you. In the case of a romantic relationship, you can use it to take your relationship to the next level (I want to move in with you) or to say that you want to be with that person forever.
Voglio vivere con te per sempre.
I want to live / to be with you forever.