Pase lo que pase, quiero que nuestra amistad siga siendo sincera.

Pase lo que pase is a very common Spanish expression meaning no matter what happens or whatever happens.

It is built from:

• pase = subjunctive form of pasar
• lo que = what / whatever
• pase again = repeated for emphasis and structure

Literally, it is something like:

• May happen what may happen

That sounds unnatural in English, but in Spanish it is a normal set phrase.

Because Spanish uses the subjunctive here.

In expressions like Pase lo que pase, the speaker is talking about:

• something unknown
• something indefinite
• something that could happen in the future

That is why Spanish uses pase rather than the indicative pasa.

Compare:

• Lo que pasa = what is happening / what happens
• Pase lo que pase = whatever happens

So pase helps create the idea of uncertainty or openness.

Lo que here means something like what or whatever.

In this phrase, lo que pase is basically what happens.
So the whole structure means:

• pase lo que pase = happen what happens → natural English: whatever happens

The lo is not referring to one specific thing. It is part of the fixed expression lo que, which often means:

• what
• that which
• sometimes whatever, depending on context

Because querer que normally triggers the subjunctive.

When one subject wants, hopes, prefers, or asks that another subject do something, Spanish usually uses:

• querer que + subjunctive

Here:

• yo quiero = I want
• nuestra amistad siga siendo sincera = what I want

So:

• quiero que nuestra amistad siga siendo sincera

This is a very standard pattern:

• Quiero que vengas
• Quiero que me escuches
• Quiero que todo salga bien

Siga siendo means continues to be or keeps being.

It has two parts:

• siga = subjunctive of seguir (to continue)
• siendo = gerund of ser (being)

So:

• seguir siendo = to continue being

This is a very common structure in Spanish:

• sigue siendo importante = it is still important
• quiero que siga siendo así = I want it to continue being like that

The two verbs are needed because the speaker is not just saying the friendship should be sincere, but that it should remain sincere.

Yes, you could, but it would mean something slightly different.

• quiero que nuestra amistad sea sincera = I want our friendship to be sincere
• quiero que nuestra amistad siga siendo sincera = I want our friendship to continue being sincere

The version with siga siendo emphasizes continuity:

• it is sincere now
• and the speaker wants that to remain true

So sea sincera is possible, but it loses the idea of staying that way.

Because sincera agrees with amistad, and amistad is a feminine noun.

So:

• la amistad
• nuestra amistad
• amistad sincera

In Spanish, adjectives usually match the noun in gender and number:

• un amigo sincero
• una amiga sincera
• una amistad sincera

Because sincera here describes an essential quality or character of the friendship, not a temporary state.

Spanish often uses:

• ser for qualities, identity, defining traits
• estar for states, conditions, locations

A sincere friendship is being described as having a genuine quality, so ser sincera is the natural choice.

That is why the sentence says:

• siga siendo sincera not
• siga estando sincera

The version with estar would sound wrong here.

Because nuestra makes it personal and specific: our friendship.

• la amistad = friendship in general, or a previously mentioned friendship
• nuestra amistad = the friendship between us

In this sentence, the speaker is talking about a specific relationship, so nuestra amistad is the natural choice.

Yes. It can be a complete expression by itself.

For example:

• Pase lo que pase, estaré contigo.
• Pase lo que pase, no te rindas.
• Pase lo que pase, seguiremos adelante.

It works like an introductory phrase meaning:

• whatever happens
• no matter what

So in your sentence, it sets the emotional tone before the main idea.

Because Pase lo que pase is an introductory clause.

In English, you would also usually separate something like Whatever happens, ... with a comma. Spanish does the same here.

So the comma helps show:

• first, the condition/frame: Pase lo que pase
• then, the main statement: quiero que nuestra amistad siga siendo sincera

Yes, definitely.

It is one of those very useful Spanish patterns that native speakers use naturally. It is worth learning as a chunk:

• Pase lo que pase = whatever happens / no matter what happens

Once you know it, you can use it in many situations:

• Pase lo que pase, te apoyaré.
• Pase lo que pase, tenemos que hablar con calma.
• Pase lo que pase, seguiré aquí.

So even though the grammar inside it is interesting, it is also a great phrase to memorise as a whole.