Denise explains: "In past times there was no expectation for love at all, it was all duty, respect."
We've moved on a bit now, or at least we hope we have, but these two pillars of a successful relationship still stand.
"Love comes and goes in all relationships but a certain amount of respect is essential.
Some people feel a sense of failure when the can't-get-your-hands-off-each-other love evaporates under the pressures of life and can overreact."
Having that level of respect for your partner will allow you to put the 'down' stages into perspective rather than giving up on them straight away.