What does "I was gonna talk to him" mean?

Question

Hi, I have a question about English expression.

In the following conversation from a TV drama Friends,
I don't know why Melissa said "I was gonna talk to him"
instead of "I'm gonna talk to him."

English is not my first language and I don't understand the reason.

Can you give me an advice?

Melissa: Umm, is Tag here?

Rachel: No. Why?

Melissa: Oh, I was gonna talk to him about doing something tonight.

Rachel: Really?! Got a little crush on Tag there do ya?

http://www.friendscafe.org/scripts/s7/705.php

Answer 1

Well, since he is not there, she can't talk to him. So it's sort of like "Well, *IF* he was here, I was going to talk to him, but since he's not here, I can't." It implies that NOW she can't talk to him. If she was planning to go hunt him down later and talk to him, she would say, "I'm going to talk to him."

Answer 2

In correct not colloquial English, she would have said "I was going to to talk to him about doing something tonight".

"gonna" is slang for "going to"

She spoke this way as she had earlier planned to have the a conversation with Tag, regarding that evening.

Answer 3

since melissa noticed teds not there, she said I 'was' gonna talk to him bec its in past tense. she was planning on speaking with him, had he been there. I'm going to would mean in the future I'm planning to speak to him