Something like "I am the only one left I go to Mexico" or "Going to Mexico lacks you", which makes no sense in either case.
This verb is used like this:

Me falta una cosa - something is missing (for me)
Me faltan varias cosas - several things are missing (for me)

Te falta una cosa - (for you)
Te faltan varias cosas

Le falta una cosa (for him/her)
Le faltan varias cosas

Nos falta una cosa (for us)
Nos faltan varias cosas

Os falta una cosa (for you guys)
Os faltan varias cosas

Les falta una cosa (for you / for them)
Les faltan varias cosas

ff

I think you have read somewher that faltar is "to need". You cannot use it as you are trying to here, which I think is "I need to go to mexico". I would say "tengo que ir a Méjico/México"

Faltar - to be insufficient, to be missing/Lacking

An example of "falta" being a need is hacer falta.

me hace mucha falta un coche - I really/badly need a car

I suppose you could say

me hace mucha falta ir a Méjico/México

Assuming your assumption is correct, he could also say "Debo ir" or "Necesito ir." Or, since "I need to..." in English can sometimes mean "I really want to" or "I feel like," he could say "Tengo ganas de ir" or something similar.

BTW, although the spelling Méjico is still used by some today, the official name of the country, as decided by the Mexican government at the time of its independence, is México. This spelling reflects the origin of the word, which was the Mexica tribe.

I wasn't too sure which is why I wrote both. Don't want to upset anybody.

ffgfdgf, Maybe what you are looking for is "Me hace falta ir a Mexico". I miss going to Mexico.

"Me hace falta ir a México" means "I need to go to Mexico", not "I miss going to Mexico".

I always understood it to mean miss. Thanks for the correction. Is it possible that in some contexts it is interchangeable?
For example: Me hace falta mi novio. Wouldn't that mean I miss or need my boyfriend'

Yes, Sally, in this case it would be miss: I miss my boyfriend.

"Falta" means something or someone that is necessary or extremely useful is missing, and its absence is a problem for you.

"Hacer falta" is much closer to "to be necessary" than to "Miss someone". Whichever or whoever is missing, makes you feel distress rather than longing.
"Echar en falta" means "to miss (something/someone)" (like "echar de menos").

"Me hace falta mi novio" is rather "I need my boyfriend".
"Echo de menos a mi novio", "Echo en falta a mi novio", and "Extraño a mi novio" (this is common in America, but not Spain) mean "I miss my boyfried".

Still pulling boyfriends! Mind you, I can see why. (This is meant to be a compliment).

I wouldn't go that far. It is not the same "Echo de menos a mi novio" and "Me hace falta mi novio". The second one is almost like an emotional emergency or necessity; the first one is just (strong) wishing.

Haha! I know your sense of humor now.

Eddy,
Es el pícaro de este forum!

Let me give you some definitions from some Spanish dictionaries:

hacer falta: ser necesario (Diccionario para la enseñanza de la lengua española - español para extranjeros)

hacer falta: (1) ser necesario (2) (raro) Echar de menos a una persona, especialmente si está muerta. (Diccionario Manuel Seco)

Hacer falta una cosa. Ser necesaria: (Diccionario María Moliner)

As you can see, you could use it instead of "miss" in a way, but expresses a much deeper sense of necessity than a simple "I miss" -much closer to an "I need".

Sally
I'm not even going to look up that word. Knowing the type of person you are, I am sure it is said in the best possible taste. (Well I hope it is).