We need to look a the surrounding verses (I have ommitted the numbers, since the numbering is different in the different versions)::
Now, Lord, you know that I take this wife of mine not because of lust, but for a noble purpose. Call down your mercy on me and on her, and allow us to live together to a happy old age. They said together, “Amen, amen.”
And now, Lord, thou knowest, that not for fleshly lust do I take my sister to wife, but only for the love of posterity, in which thy name may be blessed for ever and ever. Sara also said: Have mercy on us, O Lord, have mercy on us, and let us grow old both together in health.
Now, not with lust, but with fidelity I take this kinswoman as my wife. Send down your mercy on me and on her, and grant that we may grow old together. Bless us with children." They said together, “Amen, amen!”
The Vulgate/DR makes the “noble purpose” the desire for posterity (the blessing of children). The NABRE makes this a separate explanatory sentence for faithful conjugal love. The Vulgate also gives Sara her own prayer, rather than making Tobit’s prayer her own with her “Amen.”
Ultimately, they all say the same thing, since engaging in conjugal love with “fidelity” or “with a noble purpose” and without lust includes the embrace of a proper end of such love: the blessing of children/posterity.