Is it forbidden for a wife to prevent her husband from speaking with and looking at girls if his intention is to invite them to Islam, and is she permitted to ask for a separation if he does not desist?

What the husband is doing by establishing emotional relationships with foreign women under the pretext of inviting them to Islam is impermissible, and it is one of Satan's wiles. The fact that he intends to propose to them is not a justification, as a woman is a stranger (non-mahram (definition)) before the marriage contract. The wife has the right to prevent him from doing so, because the principle is that a woman like her should undertake the da'wah (invitation to Islam) for women, in order to block the means (to sin) and prevent fitnah (temptation).