What is the ruling on a girl marrying a young man who lives with his father and brother, knowing that the brother will leave after a year, and the father was compelled to agree?

The presence of the brother in the house does not affect the validity of the marriage. If the wife's dwelling is independent, there is no problem. If it is not independent, then an independent dwelling is a right of the wife, which she is entitled to waive. She must, however, observe caution in the brother's presence; she should not remove her hijab in front of him, nor allow him to be in seclusion with her or engage in prohibited mixing.