She's flirty in groups but goes quiet one-on-one: what to do

Look at what she actually did in the group. Did she sit next to you, pick you for the team, or only laugh at the bits everyone laughed at? Flirting in a group is often aimed at the whole table, so a joke that lands is not the same as a look that lingers. Then look at the private message itself. Was it a question she could answer in one line, or a statement that asks for a feeling in return? Short, specific, easy-to-answer messages get replies more often than warm openings that leave her to do all the work.

Also check your own pattern. If the only private contact you have is about the group night, she may be reading the thread as more of the same and not as a new chat. A mixed signal is easier to read when you have a few one-on-one exchanges to compare against. If you have had none, you do not yet know what her private warmth looks like, so do not treat silence as the verdict.

Your next message has to make a private reply feel small. Refer to something concrete from the night that only the two of you would fully get, then ask one simple question with an obvious answer, like a plan for something specific or a yes-or-no. The point is to lower the cost of answering. You are not trying to rebuild the group energy or prove you enjoyed the night, since she already knows that from the room.

Keep the tone matched to the group. If she was playful, be playful, but do not get more intense than she was in person. Let the message be easy to skim and easy to respond to from her phone while she is doing something else. If it asks her to explain herself, decide how she feels, or commit to anything large, you are asking her to do work she has not signalled she wants to do.

Wait at least two or three days before any follow-up, and longer if she has a demanding job or a busy social calendar. A second message the same afternoon reads as anxious and gives her nothing new to respond to. If she replies to the first message in any form, even briefly, you have a real thread and can build from there. If she does not reply, the second message should be lighter than the first, not a question about the silence. Something like a short line tied to a new thing, a plan, or a reason to be in touch that has nothing to do with the group.

If there is still nothing after one more follow-up spaced a week apart, stop. Do not send a third message to fix the gap or to ask if you did something wrong. Keep being pleasant if you see her in a group, since that costs nothing and keeps the door open, but let the private thread sit. Her silence is an answer, even if it is not the one you wanted.