She feels that her relationship with you is on the verge of ending.
The both of you may not have broken up yet, but there is a chance that she expects this to happen in the near future.
If these active online dating profiles are relatively new, your girlfriend may already have a sense of where her relationship with you is headed, and as a result, she is looking to have a good head start on finding a new boyfriend before the breakup happens.
It is, as long as you don’t expect the other person to take down their online dating profile as well.
When you do something like this and expect the other person that you have been on three dates with to do the same, you will be putting a lot of stress on your interaction with this person.
You should also understand that by taking down your online dating profile after going on three dates with someone, you could be setting some very strong expectations for how you want this interaction to turn out.