What is the purpose of romantic relationships?

To help release happy hormones. Lol.

In the words of Louis Armstrong ""If you gotta ask, you'll never know"

to fool us that this is a wonderful place and way to be :P

1. To fill in the gaps between sex
2. To make us feel better about not getting sex all the time or with more than one person.

Basically moat human desires, like any other animal's, can be distilled down to the essence of either food or reproduction. Humans are more complicated due to our social structure and pressure to conform to it.

Sex.

short term pain relief

human nature to love & be loved

I think it often goes something like this:

For men: sex, warmth/love and companionship.
For women: security, warmth/love and companionship.