First relationship after Long marriage 20

So I may be neurodivergent and I’m awaiting testing.

Online dating was not a thing back in the day. ( I feel OLD excuse the pun) I’m confused by the new landscape.

Connected and agreed to be BF/GF exclusive. This was confirmed on at least 3/4 occasions as I noticed she had only deactivated her account. No sex just oral giving.

My ‘girlfriend’ was talking to other men on the app we met on.

Trust went out the window for me. I did confront but phone was abruptly put down on me. Blocked and moved on … or so I thought.

I’m still upset.. 3 weeks after break up I’m still confused as to Wth happened and did I misunderstand or misinterpret what exclusive meant.

So I’m here just to clarify what exclusive means before I venture back out into OLD jungle.

Any advice appreciated.