ever since vs since then

[Offroad]

Dear teachers

Do these sentences read well?

She's been in there ever since.
She's been in there since then.

Do they have the same meaning?

Thank you

[billmcd]

Dear teachers

Do these sentences read well?

She's been in there ever since.
She's been in there since then.

Do they have the same meaning? Yes. They're OK if some action by her had been previously mentioned/established.

Thank you

b.

[Rover_KE]

They read well and have the same meaning in the right context.

Rover