the ex gf....

This guy and I have been flirty and stuff lately and he's just the sweetest. We were working one day and his ex came in ( he broke up with her about 3 weeks ago) his mood just completely changed. He was laughing and stuff with me then he was all dull and awkward and I just avoided them until she left. Then he was fine again! I think she still loves him just in the way she acts and looks at him. I feel bad for her but I don't think he feels the same way anymore. He's becoming into me ALOT.... 
His bday is today and she posted ' happy birthday to my best friend x' and a flipagram with lots of photos and videos kissing etc from when they were together.he replied with 'haha thanks _____ 🙂❤️. Great video love it. ✌️' 
Does anyone else get the vibe he doesn't like her anymore? I don't want to go ahead liking this guy if he's not interested and still likes her 
He wants to talk to me all the time tho and waits for me after work and does special little things for me. Idk anymore