Given how difficult it has been to meet a woman on a dating app you could hold a meaningful conversation with and have great dates with, you were so glad that this girl was finally bucking the trend.
They are most likely already chatting with several people on the online dating site.
When they drop off in mid-conversation, they may have decided to focus their attention on someone else that they are connecting with on a deeper level.
It may seem odd that a person would just drop off in mid-conversation with you, especially when they seemed to be so interested in you, but this isn’t an uncommon occurrence on online dating sites.