Dispute concerning a wife visiting her family

There is a woman whom Allaah has honoured with a husband who is very good. He is one of those who has the quality of gheerah (protective jealousy), but it may have gone too far. After her sister got married, he stopped allowing her to go to her father’s house, because her sister and her husband live in the same house, saying that he [the sister’s husband] might see her, although when she goes to her father’s house she sits in a separate room where her sister’s husband cannot come if she is there. If he does let her go, it is only for a very short time, and he does not let her take her abayah off, thinking that her sister’s husband might see her, even though in fact that is not possible, because her family are conservative, in sha Allaah. So the question is: is what this husband is doing correct according to sharee’ah, and is his jealousy appropriate, or is it a kind of waswasah (insinuating whisper from the Shaytaan)? Is there is a set limit within which the husband has no right to prevent his wife from visiting her father – I mean such as a maximum limit – or not? Could the husband be asked to let his wife visit her family, say, once or twice a week? Please advise us, may Allaah reward you?