What to say when she says she had a great time but feels overwhelmed

The first half of her message is the part she means, and the second half is the part she is asking for. People who feel overwhelmed rarely say that a date was bad when it was not. They are reporting that their capacity is currently low and that the pace of the connection is ahead of it. Some of that is about her week, some of it is about her history of getting swept up and then burning out, and some of it is a quiet test of whether you will respect a limit she has named.

You cannot tell from one message which of those is driving it, and you do not need to. What matters is that she has told you the pace is too fast for her right now. The useful read is that she is interested enough to say so, rather than ghosting or making an excuse. That gives you something to work with, and it also tells you the conversation is still open even though the next step has been pushed back.

Your reply has to make it clear that you heard her and that you are fine with the slower pace. That means naming the pace back to her in plain words, without repeating the word overwhelmed in a way that makes it sound like a diagnosis. It also means avoiding any question that asks her to commit to a future plan, because a question like when could we see each other next is a request for a decision she has just said she cannot make right now.

The other job is to show that the connection survives the slowdown. A brief, warm reference to something from the date, or a light comment about something you are looking forward to in your own week, does this without loading her with a task. Keep it short. The reply should feel like it costs her nothing to read and nothing to ignore for a day or two.

Send your reply the same day or the next morning, not late at night when a message can read as either intense or like you are looking for a reaction. A reply that arrives in the middle of a normal day reads as calm. Late-night messages about feelings tend to pull the conversation into a heavier place than she asked for.

After that, the timing decision is hers. Give it several days before you send anything else, and if the next message is also just a light note with no plan attached, that is usually enough. If she does not reply after two or three gentle messages spread over a couple of weeks, stop. A slower pace is something she can say yes to later. Continued silence on your end after she has already been clear is what turns a reasonable boundary into a dead end.