hey guys been seeing a girl for 2 months and recently she has gone "colder". This girl would text me, double text me, triple text me.... call me, and say things like "when can I see you again

" ect all the time (she has been super invested and chasing me the entire time we have been seeing each other)
When I got back from traveling last week ( I was in Miami for 5 days) she still came over to see me but when she left I knew something was off. We havnt hungout since... and she hasnt been "begging" to see me.
I ran into her last night at her work and she was chasing me all over the bar. but then when I was about to leave some dude came up was like all over her and when I left I saw him kiss her... So obviously there is another guy in the picture now
She still calls me (just not as often) and isn't as "available" to "hangout".
Any thoughts on how to play this or just let her go? Honestly its hard for me to see this chick as a long term option but it does suck to know someone else has stepped in. Any suggestions on how to handle this?
-Duke