Yes, swallowing saliva while kissing is perfectly normal.
Understanding Saliva Exchange During Kissing
Swallowing is a natural reflex. During a kiss, saliva naturally transfers between partners. This exchange often involves swallowing small amounts of saliva, including your partner's. The provided reference explicitly states that this is "a normal and natural occurrence during intimate activities such as kissing." [03-Nov-2018]
This doesn't mean you must swallow, but the act of swallowing saliva, including some from your partner, is a common and unavoidable aspect of kissing. The amount of saliva exchanged is typically small.
Is it Harmful?
The reference doesn't address the potential harms of saliva exchange, however, it's important to note that good oral hygiene is crucial for minimizing the risk of transmitting bacteria or viruses. Regular brushing and flossing are recommended.