Stay away from my man - no te envuelves/se envuelva con mi hombre
(formal/informal)
The above is the translation of "Do not get involved with my man", which is the general sentiment of "Stay away from my man." If you wish to translate it literally, i.e. "Keep away from my man" it would be "Aléjese/Aléjate de mi hombre." (formal/informal)
dejar a mi novio solo o te corto que
mantenerse alejado
Basically he is telling you to behave and stay out of trouble - stay away from other men.
No spinner dolphins don't say stay away
quedarse en
You can say "fuerte".
to say shoulder in spanish for a man it is hombro
This man: Este hombre.
"It's important to stay away from fats" in Spanish is "Es importante evitar grasas". It is pronounced "Ess eem-por-TAHN-tay eh-bee-TAR GRAH-sahs". Please see the Related link below for confirmation of the translation.
quedate
Donde usted permanece?
"Hombre"
Of course it is. He is in a relationship. But it is not only your responsibly. It is mainly his because he is the one in a relationship but to avoid drama I'd say stay away from it.