muchacho, I don't get this. If there's a sextile in synastry, you've got different elements--and an aspect that itself means "excitement" because it contains the 2-series as well as the 3-series.
I don't think it's helpful to suggest that people who are "unstable and confused" would be the ones to avoid "variety."
It's important to recall that unless someone marries their high school sweet heart who lives next door, many of us will find non-astrological attributes of our spouse or partner to liven things up adequately. (For example, my ex and my husband were born in countries other than mine.)
And then again, I think it's a big burden to place a demand for excitement on the other person. If people are so easily bored around a human being who genuinely loves and cares for them, then I think they've got some kind of "itch" elsewhere in the chart that they need to address independently of their relationship.
A relationship works when you want the other person's happiness as much or more as you want your own. Not when s/he's supposed to offer "variety."
I've been married 2X, once for 20 years, now just past our 21st anniversary. At our age, I don't look for "contrast" or variety in the relationship because we enjoy doing things as a couple that provide a lot of interest. (For example, we have a small RV, go camping a lot in out-of-the-way places, hiking, and lately we've rekindled an interest in multi-day canoe trips. I don't know when you last paddled on a big windy Canadian lake, or got stranded by a flash flood in a desert box canyon, but that's how we've gotten plenty of excitement.)
I think the main predictors of a successful long-term relationship are (a) shared values, and (b) genuine companionship. A spouse/partner should be one's best friend, independently of everything else entailed in a committed relationship.
This is based not only on my experience, but on couples I've known really well over the years, like family and long-term friends.
When couples get into big difficulties its usually over money or sex. Sometimes it's over whether to have children. So these are areas where conflict isn't good.