Men see it as a proof of love - and can be hurt or unsatisfied if she spits it out.
Sperm swallowing is a touchy issue, especially in hetero couples. Swallowing male/ female cum (in general), however mainly referring to sperm. From a sexual perspective, it has two meanings: 1. Accidentally different objects may end up being swallowed as well (particular high risk for small children). When in need we also swallow pills or other forms of medicine.
From a non-sexual perspective, we swallow on daily basis food, drinks and our own saliva. The process of passing through the throat, then the esophagus, of different forms of nutriments and not only.
