Darcy Fryer writes about intermarriage:

I think you ask a very good question, but I was troubled by the lack of any
reference to conversion in the article, and I would like to prod you to consider
the flip side to the question, "Why do Jews intermarry?," which is, "Why
do non-Jews intermarry?"

Obviously, non-Jews are looking for many of the same qualities in a
spouse that Jews are, and they may or may not find those qualities in
someone of the same religious background. In my observation, most
non-Jews who marry strongly identifying Jews understand what they're
getting themselves into, and many cheerfully and even eagerly
collaborate in the project of creating a Jewish home and raising Jewish
children. There are many non-Jewish spouses who fast on Yom Kippur; I
know one non-Jewish spouse who has taught Hebrew school and another one
who wants to. Some of these people end up converting eventually, after
10 or 15 years of marriage, but most do not, even though they're
familiar faces in shul and are clearly living more or less as Jews.
What is going on here?

The problem, I think, is that conversion tends to be presented to
non-Jewish partners as a one-time, either-or choice before marriage.
But whether or not to convert is just as big a choice as whom to marry
and many people do not feel comfortable making such a major decision
quickly or at the same time that they're making other major life
decisions. If the non-Jewish partner was interested in Judaism before
meeting the Jewish partner, or if the non-Jewish partner has dated
other Jews in the past, or if (not to name names) the couple in
question has been together for ten years before getting married, then
the conversion-before-marriage timetable may be realistic. But if the
non-Jewish partner's relationship with Judaism has evolved primarily
through his/her relationship with the Jewish partner, then the
timetable is not so realistic. Unfortunately, the Jewish community's
emphasis on conversion first in order to facilitate a Jewish wedding
and guarantee the Jewish status of the children makes it very awkward
for the non-Jewish spouse to go back to the rabbi two or ten or twenty
years later and say, "NOW I'm ready to convert." I suspect that in
some cases the non-Jewish spouse also finds it rather awkward to say to
the Jewish spouse, "Sorry that I wasn't ready to convert five years ago
when you wanted to have a Jewish wedding, but I've changed my mind and
I want to do it now just for my own personal growth." Moreover, since
it is possible for a non-Jewish spouse and non-Jewish parent of Jewish
children to be involved in Jewish life (such as Shabbat and holiday
observance) to a considerable extent without converting, I think many
non-Jewish spouses settle for a vaguely Jewish identity and a curtailed
Jewish religious life simply because that's what they got used to and
they're reluctant to alter the established family dynamic. If one has
already had all the children one plans to have, and one can celebrate
Shabbat and teach Hebrew school without converting, why bother?

While I agree with you that intermarriage does not have to disrupt or
compromise the Jewish partner's Jewish identity and observance, I would
also like to see the Jewish community at large recognize that not all
intermarriages need remain intermarriages. Families grow and evolve,
and non-Jewish spouses' attitude towards conversion is also likely to
evolve over time if they know that the option remains open. I know one
non-Jewish spouse who started attending tot Shabbat services with his
young son, worked his way up to leading them, and eventually converted
so that he could take on a greater leadership role in the synagogue at
large. Another long-time non-Jewish spouse finally decided to convert
when her sons reached bar mitzvah age and wanted her to go through a
public rite of passage at the same time that they were doing so. In
both of these cases, the eventual conversion was clearly the result of
a growing commitment to Jewish observance on the part of the entire
family-- and of the non-Jewish spouse feeling that s/he had license to
explore Jewish life as fully and as slowly as s/he wanted to, without
worrying excessively about legal status of wedding ceremony and
children. In general, I think this is the sort of storyline that the
Jewish community should accept and hope for in most cases of
intermarriage.