If you want to eat jam all winter, now is the time to pick strawberries.

I’ve been putting off jam making because I know the work involved. After the hunched-over picking, there is washing, destemming, and crushing to do. Then I’ll put my two sons down to nap and let my two daughters help me stir berries into sugar for precisely 10 minutes, while I boil pectin on the stove top. We’ll combine our efforts and begin pouring into jars. To get through a year, we’ll have to freeze no fewer than 24 jars. In order to be generous, we’ll need another dozen.

But if I don’t get to work soon, I won’t have a freezer full of jam and the promise of sudden sweetness on my toast all winter long while I wait for summer to return.

Perhaps it isn’t a coincidence that the season for strawberries is also the height of wedding season. New love is a sweet fruit you feel fortunate to find. For some, it is the result of patient cultivation after waiting for someone’s interest to ripen. For others, love surprises us in places we hadn’t thought to look. Either way, those who are wise know that this season of early enthusiasm will not last forever. Love is too sweet a fruit to grow all year long. When love ripens, we celebrate it at once and work to preserve it for later. Marriage seals the lid on a feeling we want to preserve.

My husband and I got married 12 years ago on an unusually hot Sunday in May. We grinned and made a vow that we would sustain our love “in sickness and in health” and “for richer and for poorer.” We made the promises in good faith even though we had only ever tasted the sweeter side of love.

It is right and good that love should be permanent. Shakespeare describes marriage as an action that honors the true nature of love, because love is supposed to be an “ever-fixed mark” that does not “alter when it alteration finds.” Solomon claims that “love is strong as death” (Song of Solomon 8:7) and what could be more permanent than that? But anyone who has been married knows that the in-love feeling is not always in season.

Marriage changes our feelings of optimism and good intentions into something more lasting–a promise. Jesus recalls marriage as God’s original institution, saying that from creation it was God’s intent that “the two shall become one flesh” (Mark 10:8). This is more than a mere promise, it is an alteration of the very nature of these two people into something else entirely. Like sugar and pectin alter the strawberries into something that can last far into the future, marriage is a recombining of two separate lives into one new life that cannot be separated. By Him we are joined into something new, something that will endure.

One of the privileges of being a pastor’s wife is meeting new couples on the cusp of marriage. We can see their optimism about marriage and we do not want to rob them of this season of anticipation. But we try to prepare them for the road ahead. We talk about the importance of forgiveness and try to map out all the common frustrations they are likely to face. We bear the bad news that one day soon a cold wind of bitterness or loneliness or disappointment will sweep into their homes and the sweet fruit of love will no longer be easy to find.

Marriage makes us promise that we won’t forget the good feelings while we’re waiting for them to be in season again. Marriage is a promise to persevere. The promise is made in a season where love is easy to find so that when love is more difficult to feel, we will have stored up our good will towards one another. The promise we make is an act of preservation. Marriage declares love to be good and worthy of protecting, but marriage also anticipates the changing seasons and feelings.

That’s why I think of marriage like strawberry jam. We take something sweet and make it more lasting so we can experience sweetness spread out over a whole life time.