kazoku to issho ni bangohan o taberu to, totemo shiawase desu.

I feel very happy when I eat dinner together with my family.

Breakdown of kazoku to issho ni bangohan o taberu to, totemo shiawase desu.

• です: to be
• を: direct object particle
• 食たべる: to eat
• と: companion particle

Questions & Answers about kazoku to issho ni bangohan o taberu to, totemo shiawase desu.

What does the と after 家族 mean here? Is it “and” or “with”?

In 家族と一緒に晩ご飯を食べると、とても幸せです。, the と after 家族 is the “with” particle, not “and”.

• 家族と = “with (my) family”
• It marks a companion:
  
  • 友だちと映画を見ます。 = “I watch a movie with my friend.”

So 家族と一緒に literally means “together with (my) family.”

Why is 一緒 followed by に? What does 一緒に do?

一緒 (いっしょ) by itself is a noun meaning “together / same.”
When you add に, it becomes an adverb:

• 一緒に = “together (with someone)”

In the sentence:

• 家族と一緒に晩ご飯を食べる
  = “(I) eat dinner together with (my) family.”

So the structure is:

• [person] と 一緒に [action]
  = “do [action] together with [person].”

There are two と in the sentence. Do they mean the same thing?

No, they have different roles:

1. 家族と一緒に

   • This と = “with” (companion marker).

2. 晩ご飯を食べると、

   • This と is a conditional particle, meaning “when / whenever / if”.

So:

• 家族と一緒に晩ご飯を食べると、
  = “When I eat dinner together with my family,”
• とても幸せです。
  = “I am very happy.”