Ella se va de la fiesta muy tarde.

Ir means to go (somewhere), but irse means to leave / to go away (from somewhere).

• Va a la fiesta = She goes to the party. (destination)
• Se va de la fiesta = She leaves the party / goes away from the party. (origin she’s leaving)

With the idea of leaving a place, Spanish normally uses irse (de), not just ir. So Ella se va de la fiesta muy tarde is natural; Ella va de la fiesta muy tarde is not.

Here se is a pronominal pronoun that is part of the verb irse. It doesn’t literally mean “herself” in this context.

• Base verb: ir = to go
• Pronominal form: irse = to leave, to go away

So:

• Ella va = She goes.
• Ella se va = She leaves / She’s going away.

You don’t translate se separately; you just learn irse as its own verb meaning “to leave.” It’s often called “reflexive” in textbooks, but in many cases like this it’s better to think of it as a fixed part of the verb that changes the meaning.

Yes, in standard Spanish that sounds wrong or at least very strange.

• To say leave a place, you say irse de or salir de:
  • Ella se va de la fiesta muy tarde.
  • Ella sale de la fiesta muy tarde.

Ir de la fiesta doesn’t work for “leave the party.” Without se, ir de would need some other meaning (e.g., in some fixed expressions like ir de compras = “to go shopping,” but that’s different).

Both can be translated as to leave the party, but there’s a nuance:

• irse de la fiesta
  
  • Focuses on the idea of going away, no longer being there.
  • Very common in everyday speech.
• salir de la fiesta
  
  • Literally “to go out / exit from the party.”
  • Slightly more neutral/physical: the act of going out.

In your sentence:

• Ella se va de la fiesta muy tarde.
• Ella sale de la fiesta muy tarde.

Both are correct and natural in Latin American Spanish. Irse is probably the more common choice in casual conversation.

Because the idea is leaving FROM the party, not going TO the party.

Spanish tends to use:

• ir a = to go to a place
  
  • Ella va a la fiesta. = She goes to the party.
• irse de / salir de = to leave from a place
  
  • Ella se va de la fiesta. = She leaves the party.
  • Ella sale de la fiesta. = She exits/leaves the party.

So de matches the idea of “from” (origin), and a matches “to” (destination).

De la fiesta and de fiesta mean different things:

• de la fiesta = from the party (a specific party)
  
  • Ella se va de la fiesta muy tarde.
    → She leaves the party very late.
• de fiesta (without article) = out partying / having fun / celebrating (general activity)
  
  • Ella se va de fiesta todos los fines de semana.
    → She goes out partying every weekend.

Your sentence refers to a particular party, so it needs la: de la fiesta.

Yes, that’s possible:

• Ella se va de la fiesta muy tarde.
• Ella se va muy tarde de la fiesta.

Both are grammatical. The most natural order for many speakers is the original one, keeping de la fiesta (the place) close to the verb and putting the time expression muy tarde at the end.

Word order in Spanish is flexible, but a good guideline:

1. Verb + essential complements (like de la fiesta)
2. Then time or manner expressions (like muy tarde)

Hence the original sounds especially natural: se va de la fiesta muy tarde.

Spanish simple present can cover several uses:

1. Habitual action

   • Ella se va de la fiesta muy tarde.
     → She (usually) leaves the party very late.

2. Future with a time expression (especially when the time is clear from context)

   • Mañana ella se va de la fiesta muy tarde.
     → Tomorrow she leaves the party very late.

3. Narrative/description (talking about what happens in a story, plan, schedule, etc.)

If you really want to emphasize future, you can say:

• Ella se va a ir de la fiesta muy tarde. (She is going to leave very late.)
• Ella se irá de la fiesta muy tarde. (She will leave very late.)

But se va is often enough, especially with a time reference.

You can drop Ella. Spanish usually omits subject pronouns when the subject is clear from context or from the verb ending:

• Ella se va de la fiesta muy tarde.
• Se va de la fiesta muy tarde.

Both are correct.

You use ella when you:

• Need to be clear who you’re talking about (she vs. he vs. you).
• Want to emphasize she, as opposed to someone else.

In muy tarde, tarde is functioning as an adverb of time (“late”), not an adjective.

Spanish often uses the same form for the adjective and the adverb:

• Temprano = early (adj./adv.)
• Tarde = late (adj./adv.)

So:

• Ella llega tarde. = She arrives late.
• Ella se va muy tarde. = She leaves very late.

You don’t need a special adverb form like lately; tarde already works as the adverb “late.”