For most of the twentieth century, Anglo-Indian families met each other without trying. The railway colonies, the schools, the clubs, the parish — everybody knew everybody, and marriages came out of that as naturally as anything else.
That structure is largely gone, and nothing replaced it.
What actually changed
The institutions dispersed. Railway employment fell away, and with it the colonies that put hundreds of families in one place. The schools remain but the community around them thinned.
Emigration split the families. Australia, the UK, Canada, New Zealand. Most families now have members on two or three continents, and the cousins who would once have introduced you live eleven time zones away.
The clubs aged. The institutions that remain skew older. A twenty-eight-year-old walking into one is not going to meet somebody their age.
The parish stopped being the network. Congregations are smaller and mixed, and the parish that once knew every family now knows a handful.
Why the usual advice does not help
"Meet people through friends" assumes there are Anglo-Indian friends to meet people through. For a family in a city with a dozen households left, there are not.
"Try a matrimonial site" assumes the site has anybody from your background. Type the community into a large Indian matrimonial site and you get either nothing or a handful of profiles scattered across four countries.
The problem is not that people are unwilling. It is that they are not in the same place, and there is no longer anything that gathers them.
What that means practically
Two things follow, and they are not comfortable.
Geography cannot be a hard requirement. If you insist on somebody in your own city, for most Anglo-Indian families the search ends before it begins. Being open to another city, or another country, is not a compromise — it is the only way the arithmetic works.
Somebody has to do the introducing. In a large community, people find each other. In a small and scattered one, they need to be introduced deliberately, by someone who knows who is looking.
The community is not too small for anyone to find a match. It is too spread out for anyone to find one by accident.
That is the difficulty, and it is a solvable one — but it is not solved by waiting for it to happen the way it used to.