I've never seen or heard it presented in the terms of "being allowed". I would rather suggest that adherents are somewhere from "strongly dissuaded" to "forbidden" from doing so.
Can you seriously suggest that if a man went to the BKWSU and found a nice, good looking BK Sister, that he could court that women ... and then when they went to the Seniors to tell them they wanted to get married, the Seniors would sanction it?
You're joking, surely? I've never even heard of it being an "official policy" ... even in order to cheat immigration (although, yes, we both know that has happened and disastrously). That's just another one of those grey areas in which the BKs operate in a semi-criminal manner which you'll never find written down anywhere.
The Murli quote from Lekhraj Kirpalani is that it is "
better to get married than burn with lust" (by which I presume he means going off and having affairs or visiting prostitutes), meaning that if at the very last resort you cannot give up lust and attachment, it is better to get married. It is by no means a suggestion or even allowance.
I can think of one "official" BK marriage which was arranged by Lekhraj Kirpalani (of trustee/account BK Ramesh Shah to BK Usha) but, to the best of my knowledge, the practise was stopped because too many of such couples left the Yugya. The marriage of BK Ramesh Shah to BK Usha was to trick, fool or placate the parents of Usha to stop them arranging a different marriage to a non-BK who would have expected her to carry out full conjugal responsibilities. Perhaps others have happened in India, I don't know. We are talking about, what, two or three cases out of 1 million followers?
The great contradictory (oxymoron) surely is that "marriage" is a binding of two individuals as one based on love, attraction and attachment ... whilst the BKs are entirely against those and their path about the separation of all individuals. Never mind the idea of sex and affection being OK.
My reading of the situation is that it is about,
a) presenting a certain facade to the public, and
b) control over adherents and particularly their finances.
i) If you come into the BKWSU as part of a couple, they want you to stick together because it looks better, more respectable for them.
ii) If you come into the BKWSU as an unmarried couple, they want you to immediately stop because to them an unmarried couple, "living in sin" or boyfriend-girlfriend situation, look bad.
iii) If you are single, they want you to stay single and will come down on you like a ton of bricks if you start to become attracted and form a relationship with a BK of the complimentary sex.
Please correct me if I am wrong, but where such attractions do arise, they were normally treated with a 6 month ban from seeing each other and/or one of the individuals being sent away to another center. Any individuals having such attractions are expected to confess them to center-in-charge or Senior Sister ... and likely be snitched upon by other BKs. And, yes, I speak from direct personal experience of it.
Because I don't think BKism has any particular spiritual benefit, I see this purely as a management of resources, i.e. the adherents time, money and resources (such a property). The BKs want it all, or as much as they can get and they do not want anyone else "pulling the intellects" of their adherents (meaning distracting or questioning influences).
Married couples or individuals have always seen seen as "half" Kumars or Kumaris and, in my opinion, treated as a bit of a second class.
It does seem to be that in the West the BKs are becoming a bit more relaxed. I also put this down to financial security,, i.e. they have enough money, properties, unpaid workers and so don't need to control as much as they did whilst they were building themselves up ... and, indeed, they have discovered that it is more profitable ($$$) to be or appear more normal (tolerant and accommodating) and less cult-like.
However, I do not think for one minute that reflects their actually inner beliefs and teachings, nor that the leaders have any consideration or care for what might happen to their adherents in their old age or infirmity.
In addition to which, given that as many of 5% of human being have homosexual tendencies, I have no idea how all this effect them.
Gay celibate BK marriages any one?