Spanish phrase
Lo siento mucho.
Meaning
I'm really sorry.
When to use it
A strong, casual apology showing sincere regret. Used with friends or family for personal mistakes, informal and warm.
Example dialogue
Lo siento mucho, me comí tu almuerzo.
I'm really sorry, I ate your lunch.
¡No pasa nada, la próxima avísame!
It's okay, just let me know next time!