Is allowing a situtation that may cause sexual arousal without seeking the arousal a mortal sin, venial sin, or not a sin at all?
If it is not your intent to be aroused, and the situation is not intended to cause arousal, then it is not a sin.
Discuss the particulars with your confessor.
There is more involved (such as what is the reason…is it a near occasion to consent to such etc etc).
There are many distinctions to make. If you want to date a beautiful girl, and you ask for this reason, you’re probably just fine.