Saying that you are his girlfriend would feel too final and he doesn’t believe that dating you for 6 weeks has been a enough time to declare you to be his girlfriend.
Calling you his girl feels a lot safer as it doesn’t feel quite as official.
The only reason why anyone would be disappointed if their online date was short would be that they were unaware that their online date was short in the first place.
This means that their online date was not being honest when they filled out their height on their bios in their online dating profiles.
You have to be honest in your online dating profile.
They have gotten to the point where they are alright with meeting this person in real life at a public place, but they aren’t sure that this is a person that they want to have their phone number.
By meeting without giving a phone number, they are acknowledging that there is interest, but there is yet to be trust established.
When a person agrees to meet on a date in real life without giving a phone number beforehand, they are indicating that they aren’t ready to take their interaction to the level of exchanging phone numbers quite yet.