Supernatural Romance

In stories where some characters are immortal – i.e. living for a very long time without aging – the subject of romance can be a touchy topic. It is hard to find people with shared life experience when everyone else measures life in decades rather than centuries. There is often a question of power imbalance when one side of a relationship is so much older than the other.
On the other hand, an immortal character finding romance with a regular mortal is an example of love bridging gaps. It means the immortal has chosen to care about people, even though he will outlive all of them.
Examine arguments for and against these age-gap romances. Examples include Buffy the Vampire Slayer, Twilight, the Immortal and Dupli-Kate from Invincible, Thor and Jane Foster from Marvel, and more.