Have you ever heard someone said
“Of course, I DO love it” / “I DO wanna go with you but …
That’s bad grammar, right?
At school, we’re trained to say
“I love pizza.” not “I DO love pizza”
“She likes him” not “She DOES like him”
Obviously, because it is grammatically wrong!
But why do native speakers say it?
What does it mean when people use this “incorrect” grammar form?
Well, “Do/ Does or Did + verb” means “to emphasize”
It is to emphasize, confirm, or add more weight to the verbs.
So The difference between the normal grammar form and this form is “feelings”
When someone says “I tried.” it doesn’t feel as serious as “I DID try.”
In other words “do, does, did + verb” means “really”
I really tried. / I really did try.
For examples
EX1
Girlfriend: Hey, why didn’t you call me this morning? I feel like you don’t care about me anymore.
Boyfriend: No no, I DO care about you! but I just got some work to do this morning.
So “I DO care about you” means “I really, truly, seriously, honestly care about you.”
It is to ensure, to confirm the fact that he cares.
EX2
Boyfriend: Let’s order pizza for dinner!
Girlfriend: hmmm. I’m not feeling it.
Boyfriend: What? I thought you love pizza.
Girlfriend: I DO love pizza of course! but I just feel like we should eat something healthy today.
So, “I DO love pizza, but …” is to confirm the fact that she really loves pizza, still loves pizza, it hasn’t changed. But she just feels like eating something else today.