Ahsanallahu ilaykum Shaykh really I’ve no way to get my wife back from the states to Europe. I read a wife must join the husband. Is then this considered a necessity for her to travel alone? If not then I can’t take her back

If you will sit there for a long time and there is no way at all to bring her or a mahram to accompany her and you pay for them both, and you are afraid from falling into thay which forbidden then, yes and I advise you to seek the answer of someone else, see if he agrees with me or not that it is allowed in such a case with the condition that it is 100% safe for her.