Hi so basically you have a problem with trust. It is very important for a person to be comfortable by themselves and know that they have everything that they need for the person that God put them with. They are not in any way an adequate for that person that God has put them with. It is also very important that before engaging in a relationship that you make sure that they have a very personal relationship with God because they will not have those types of tendencies. It is also important for you to know that if a person leaves your life or wants to leave your life they are not the person for you so it is a blessing that you realize that before you marry because you cannot remarry you can only be with one person. Once you have confidence in yourself and confidence in the person that you are courting and you should live separately until you know that it's time to marry you will have the insurance that you need. Every person wants to be cared and love for as they should be and that is in a Godly manner. The person that loves you and you love and you both act according to God they will not want to leave you they will not look at anybody else in that manner they will not have the desire to. When you find that person that has no desire to look at another individual in the way of a relationship then that is probably the person that you're meant to be with and you can invest yourself will hardly if ever that person disappoints you always remember that you can have friends and a relationship with God can sustain you through life. We are in Revelations and I understand that everybody wants a special somebody with them but the most important thing for you is to make sure that you're in accordance with God and to love yourself.