Praise be to Allah.
First of all, before answering this question I would like to point out that all matters are in the hand of Allaah; no benefit comes and no harm is warded off except by His help. The One Who relieves distress is Allaah, so if anything befalls a person he must turn to Allaah and beseech Him and call upon Him, whether that has to do with attaining something desired or removing something disliked.
Allaah says (interpretation of the meaning):
“And whatever of blessings and good things you have, it is from Allaah. Then, when harm touches you, unto Him you cry aloud for help”
“Is not He (better than your gods) Who responds to the distressed one, when he calls on Him, and Who removes the evil, and makes you inheritors of the earth, generations after generations? Is there any ilaah (god) with Allaah? Little is that you remember!”
Allaah is the One to Whom the slave turns. When a person turns to Him with sincerity and humility, acknowledging his need for Him, and his food, drink, clothing and shelter are all good (i.e., from halaal sources), then he may expect Allaah to respond. This applies to all kinds of du’aa’.
Then we should note that if a person calls upon Allaah and He does not respond, then either Allaah is storing that up for him [for the Hereafter], or He is warding off from him some evil that is greater than what was asked for. But he should not despair and give up calling upon Allaah, for Allaah loves those who persist in du’aa’ and who await His response with certain faith. For Allaah says (interpretation of the meaning):
“And when My slaves ask you (O Muhammad) concerning Me, then (answer them), I am indeed near (to them by My Knowledge). I respond to the invocations of the supplicant when he calls on Me (without any mediator or intercessor)”
He should seek out the times when prayer is answered. One of these times is the last third of the night. The Prophet (peace and blessings of Allaah be upon him) said: “Our Lord descends to the lowest heaven when there is one third of the night left, and He says, ‘Who will call upon Me, that I may answer? Who will ask of Me, that I may give to him? Who will seek My forgiveness, that I may forgive him?’ – until the dawn comes.” (Narrated by al-Bukhaari, 7494; Muslim, 758)
Similarly: “The last hour of Friday – there is no Muslim slave who stands and prays and calls upon Allaah at that time, but Allaah will grant that to him.” (narrated by al-Bukhaari, 935; Muslim, 852)
Or from the time when the imaam comes out on Friday until the prayer ends.
Another of these times is the interval between the adhaan and iqaamah, as the Prophet (peace and blessings of Allaah be upon him) said: “Du’aa’ made between the adhaan and iqaamah will not be refused.” (narrated by al-Tirmidhi, 212; Abu Dawood, 521; Ahmad, 3/119. al-Tirmidhi said, (it is) a saheeh hasan hadeeth).
Among the situations (when du’aa’ is answered) is when a person is prostrating. The Prophet (peace and blessings of Allaah be upon him) said: “With regard to sujood, offer lots of du’aa’ then, for it is more likely that you will receive a response.” (Narrated by Muslim, 479). Another occasion is after saying the final tashahhud (in prayer) and before saying the salaam. The Prophet (peace and blessings of Allaah be upon him) said, “Then let him say whatever du’aa’ he wants.” (Narrated by al-Bukhaari and Muslim).
This is what I wanted to say before answering this specific question.
With regard to the answer to this particular question, this woman has to have patience and seek reward with Allaah. She should realize that all matters are in the hand of Allaah and that the delay in getting married may be better for her and it may ultimately lead to something good that Allaah has prepared for her. She should be optimistic and expect good things to happen. If you feel some distress or waswaas (insinuating whispers from the Shaytaan), then increase your dhikr (remembrance of Allaah), seek refuge in Allaah from the accursed Shaytaan, and focus on worship and other good deeds, until your distress is eased.
Also, pray the well known du’aa’ for relief of anxiety and distress (“Allaahumma inni ‘abduka ibnu ‘abdika ibnu ‘amatika, naasiyati bi yadika maadin fiyya hukmuka (O Allaah, I am Your slave, son of Your slave and son of Your maidservant. My forelock is in Your hand. Your command over me is forever executed…)”). A woman should say, “Allaahumma inni amatuka bintu ‘abdika bintu amatika naasiyati bi yadika maadin fiyya hukmuka, ‘adlun fiyya qadaa’uka. As’aluka bi kulli ismin huwa laka sammayta bihi nafsaka aw anzaltahu fi kitaabika aw ‘allamtahu ahadan min khalqika aw ista’tharta bihi fi ‘ilm il-ghaybi ‘indaka an taj’al al-Qur’aan al-‘azeem rabee’a qalbi, wa noora sadri wa jalaa’a huzni wa dhahaaba hammi (O Allaah, I am Your maidservant, daughter of Your slave, daughter of Your maidservant. My forelock is in Your hand. You command over me is forever executed and Your decree over me is just. I ask You by every name belonging to You which You have named Yourself with, or revealed in Your Book, or You have taught to any of Your creation, or You have preserved in the knowledge of the unseen with You, that You make the Holy Qur’aan the life of my heart and the light of my breast, and a departure for my sorrow and a release for my anxiety).”
(Narrated by Ahmad, 1/452, 391; Ibn Hibbaan, 3372; al-Haakim, 1/509. classed as saheeh by al-Albaani in al-Silsilah al-Saheehah, 199).
And there are other du’aa’s which have been narrated from the Prophet (peace and blessings of Allaah be upon him). This will relieve you of the distress and anxiety that you are suffering. We ask Allaah to keep you and us safe and sound. And Allaah is the Source of strength.