Do women sleep with babydaddy if he has a woman?

I dont know why.. But I will always think my boyfriend is sleeping with his baby mama behind my back. I really don't know why. They never hang out that I know of. But he also doesn't take me with him to drop the kid off. Also, we've been together for 2 years and she STILL hasn't moved on. She is just patiently waiting for him and I to break up so she can have him again. Do you think they still sneak around? Their texts are somewhat flirty.. Can't tell if he is just being nice.