Whats going on in his head?

My boyfriend of a year has been trying to message other girls from his work.. 2 weren't interested , 1 was.. he's 36 there all early 20s.. while this was happening he got my name tattooed on his chest. He's also made a fake Facebook and messaging girls of there , saying he's single.. there sexy etc... Tbf these girls are not even good looking. Some are of Asian decent.. I don't know what's going on.. he can't even stand other men looking at me. When we're together he's all over me and tells me sweet lies obviously.. he even tells his family that I'm the 1 , and he doesn't wanna sleep with anyone else.. if that's the case what's going through his head messaging other girls... I'm 34 by the way. His actions are confusing me. Why get my name tattooed but message other girls wanting to meet? He tells lies about stupid things aswell.. I say he's a pathological liar.. he does also have ADHD, and an emotional and mood instability disorder
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Bit more background... He is good looking , goes gym etc.. I know he's a cheat. . . But his behaviour towards me totally counteracts what he's doing.. it's more that I can't understand his behaviour.
Whats going on in his head?
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