Marriage is generally based on more equality and deeper friendship than in the past, but even so, it is hard for it to compensate for the way that work has devoured time once spent cultivating friendships.

In personal life, the warm glow of nostalgia amplifies good memories and minimizes bad ones about experiences and relationships, encouraging us to revisit and renew our ties with friends and family. It always involves a little harmless self-deception, like forgetting the pain of childbirth.

I've had the kind of complex life I write about. I was a single mother for 12 years. I'd been engaged. The wedding fell through. I then discovered I was pregnant and opted to have the child on my own. I was a professor. I was in my mid-30s. I could manage it financially.

The closer we get to achieving equality of opportunity between the sexes, the more clearly we can see that the next major obstacle to improving the well-being of most men and women is the growing socioeconomic inequality within each sex.

There is no denying that we have made great progress toward gender equality.

As time passes, the actual complexity of our history - even of our own personal experience - gets buried under the weight of the ideal image.

Over the ages, some societies have accorded far less value and respect to singles than to married individuals.

As Americans lose the wider face-to-face ties that build social trust, they become more dependent on romantic relationships for intimacy and deep communication and more vulnerable to isolation if a relationship breaks down.

Especially around Valentine's Day, it's easy to find advice about sustaining a successful marriage, with suggestions for 'date nights' and romantic dinners for two. But as we spend more and more of our lives outside marriage, it's equally important to cultivate the skills of successful singlehood.

Labeling people single parents, for example, when they may in fact be co-parenting - either with an unmarried other parent in the home or with an ex-spouse in a joint custody situation - stigmatizes their children as the products of 'single parenthood' and makes the uncounted parent invisible to society.

Throughout history, people with few educational or economic resources and little bargaining power have often looked to authoritarian, ruthless people to stand up for them.

Investing in living-wage jobs and reducing the inequities between local school districts would give young people more, not less, incentive to postpone childbearing and more possibilities for independence.

Giving married women an independent legal existence did not destroy heterosexual marriage. And allowing husbands and wives to construct their marriages around reciprocal duties and negotiated roles - where a wife can choose to be the main breadwinner and a husband can stay home with the children - was an immense boon to many couples.

Contrary to myth, 'The Feminine Mystique' and feminism did not represent the beginning of the decline of the stay-at-home mother but a turning point that led to much stronger legal rights and 'working conditions' for her.

A primary motivation for introducing no-fault divorce was, in fact, to reduce perjury in the legal system.

Unilateral divorce has decreased the bargaining power of the person who wants the marriage to last and has not engaged in behavior that meets the legal definition of fault. On the other hand, it has increased the bargaining power of the person who is willing to leave.

Whatever their relative valuation of the single and married states, most societies in history made sharp distinctions between those who married and those who remained single: They were seen as mutually exclusive ways of life, with different legal rights and social obligations.

It no longer makes sense to see singlehood and marriage as two distinct and stable social categories that should be accorded different legal rights and social esteem.

Valentine's Day is a perfect time to reject the idea that the ideal man is taller, richer, more knowledgeable, more renowned, or more powerful.

Usually, Valentine's Day comes and goes with just a day or two of news media attention to courtship and marriage.

The notion that marriage is an impediment to commitments to the larger community is a long-standing one - and one reason early Christians did not place the institution at the top of their moral hierarchy, complaining that married couples cared more about pleasing each other than doing the Lord's work.

Marriage can provide a bounty of emotional, practical, and financial support. But finding the right mate is no substitute for having friends and other interests.

Marriage is no longer the main way in which societies regulate sexuality and parenting or organize the division of labor between men and women.

In my work as a historian and in my relationships as a friend, teacher, wife, and mother, I have come to think that the most useful way to understand the past and make it work for you is to look at the trade-offs and contradictions that, however deeply buried, can be uncovered in every memory, good or bad.

Couples need time alone to renew their relationship. They also need to sustain supportive networks of friends and family.

When liberals dismiss all Trump supporters as racists, this only fuels their anger.