My partner doesn't check on me at times where I need it most. How do I ask for this without bringing up my past?

With my past relationship, he is very attentive. He checks on me every time we go out since he knows I get overstimulated and overwhelmed easily. When I get quiet, he always ask if I am okay or if I need anything.

But my partner now is quite the opposite. He doesn’t do any of those. I don’t know how to say it to him without bringing up about my past experience.