If my ex girlfriend can't find a ride with her friends then I'm just going to let her travel by foot.
Why not give your ex a ride home instead of having them walk? Did she do something to upset you?
No, I only want to finish the road trip as soon as possible without any drama.
I understand wanting to avoid drama and tension on a road trip, but leaving someone to walk alone somewhere is dangerous for them. Giving her a ride would be a safe and kind thing to do so that she can get to her destination.
I don't care and my decision makes sense to me. In fact, I hope she gets harassed along the way.
Being upset at an ex is normal, especially if the breakup went poorly. However, she is still a person and doesn't deserve to be harassed or put in dangerous scenarios. If you don't want to give her a ride, why not at least call for a cab to take her to where she needs to be?