Can she go to Jeddah without entering ihram, then go back to her miqaat and enter ihram?

If the matter is as you describe, then she has two choices, and may do that which suits her better:

The first choice, which is the best, is that she should do Hajj tamattu‘. So she should intend to do ‘umrah when she passes the miqaat, and go to Jeddah when she is in ihram, and her husband should not be intimate with her. Then she should go to Makkah, and when she has finished ‘umrah, she should cut her hair and exit ihram, whereupon it will be permissible for her husband to have intercourse with her if he is not in ihram. On the eighth day of Dhu’l-Hijjah (yawm at-tarwiyah), she should enter ihram for Hajj from wherever she is, whether she is in Makkah or Jeddah.

The second choice, is that she may come to Jeddah from Egypt without entering ihram, and her husband may have intercourse with her in that case, so long as he is not in ihram. Then if she wants to do Hajj, she should go to her miqaat [Rabigh] and enter ihram for Hajj from there.

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) was asked: If someone passes the miqaat knowingly and deliberately, but he wants to rest – such as if he passes the miqaat of Qarn and goes to ash-Sharaa’i‘, so that he can rest at his relatives’ house, then he goes back to the miqaat and enters ihram from there, because he intends to do Hajj or ‘umrah – is he sinning by passing the miqaat, or is there some leniency in the matter?

He replied: No, there is some leniency in the matter, meaning that the best is not to pass the miqaat without entering inraam, and he can rest at his relatives’ house whilst in ihram. People do not see anything wrong with that, so there should be no embarrassment or shame. But if he does that, and says: I shall go and rest now, and I will go back to the miqaat and enter ihram from there, there is nothing wrong with that.

Questioner: Even if that is for a week?

Shaykh: There is no reason why he should not do that. What matters is that he is passing the miqat, but his intention is to go back and enter ihram from there.

Question: He has to go back to the miqaat that he passed?

Shaykh: He has to go back to the miqaat that he passed.

Question: Whether it is near or far?

Shaykh: Whether it is near or far." (Liqa’ al-Baab al-Maftooh 93/26).

It should be understood that for the pilgrim who has entered ihram for Hajj or ‘umrah, it is prohibited for him to have intercourse or do any of the things that lead to it. This has been explained in the answer to question no. 11356 .

And Allah knows best.