It is not permissible for a woman to form a relationship with a man who is not permissible for her, even if it is with the intention of getting married in the future, because these relationships involve things that are haraam and wrong, such as looking, touching, enjoying listening, infatuation, soft speech and other things that are not pleasing to Allah, may He be exalted.
The gifts that you received are subject to further discussion.
1. Whatever was taken in return for the haraam relationships that involved the evils that you have mentioned, if it is still with you then you have to get rid of it by giving it to the poor and needy. Whatever has been used up or spent, you do not have to do anything with regard to it.
This is the basic principle with regard to the one who has acquired wealth through haraam work and it was given to him by the other party willingly, such as payment for singing and dancing and the like. The money should not be given back to the one who gave it, and the one who took it should not benefit from it because it is wealth that he took in an evil manner.
The gifts that men give in haraam relationships are only given in return for enjoying the continuation of that relationship, seeing the woman, going out with her, talking to her and so on. They are given willingly in return for something haraam. The most correct scholarly opinion on that is what we have mentioned, that one should get rid of them.
2. Gifts that came after engagement; if the fiancÃ© asks for them, they must be given back to him, but if he does not ask for them then they become your property.
See also the answer to question no. 101859
We ask Allah to help and guide you.
And Allah knows best.