I mark the first sense as obsolete because speaking truthfully, no one uses it that way anymore. Given I first met the word in Elizabethan poetry and spend time at Renn Faires, however, the amorous meaning comes first to my mind. Possibly not to others, however -- the primary meaning in modern English is the second. Frankly, I'm not sure I approve of this diminution of the word -- the language needs more loving. Especially in times of war:
The slow campaign provided ample opportunity for dalliance with civilians.
Dates back to the early 14th century, when it was spelled/pronounced closer to daliaunce, from Anglo-Norman dalier, to chat, of unknown origin -- which makes sense given English is, famously, what you get when Norman soldiers try to pick up Saxon girls.