Fear can be a factor. A number of recent polls indicate as much. And I am also aware of it from a variety of personal observations.

If your parent's marriage was filled with strife,
if you see marriages among your friends come apart painfully,
if your wages are being eaten up by inflation and housing costs are through the roof,
if you cannot depend on your extended family to provide much support,
if the prospects for steady employment are uncertain,
if unhealthy and unhelpful habits persist --
any of these and more can result in significant misgivings about whether your relationship can go the distance or whether even you yourself will be able to fulfill your role adequately as a spouse or parent. Cohabitation appears to offer close companionship with an escape hatch.

So surely one way to provide support for marriage is to draw out, validate, and thoroughly address with care the particular fears that young people have as they anticipate the possibility of getting married.

"For which of you, desiring to build a tower, does not first sit down and count the cost, whether he has enough to complete it?" (Luke 14:28 ESV).

Some congregations identify mature married couples who are able and willing to mentor young couples. Other congregations host marriage workshops on their own site or publicize marriage workshops elsewhere. And for any couple who needs it, a congregation could establish a Marriage Support Fund that underwrites the cost of participating in the workshops or in any other activity that promises to help fortify their relationship.