A'salamu alaykum. Our beloved Nabi salaAllahu alayhi wa salam said, "You will be with who you love." It is hard to understand because we only have a little bit of knowledge, that Allah chose to give to us. Jannah is Jannah, you won't feel any hurt, or sorrow, or worry, etc. It's absolutely nothing like this dunya, nothing we ever felt before. If we make it there, in sha Allah. If you truly want to be with your parents in Jannah, don't be afraid of giving them dawah. Give it your best effort to bring them to Islam, even by just constantly making Dua for them. As for being in a pre-marital relationship, there is only one kind of love and that is love for the sake of Allah. Think of that relationship as a lesson for you, it wasn't truly love. Repent to Allah, and go closer to Him. When you love someone for the sake of Allah you will be with them in Jannah, in sha Allah. When you sacrifice something for the sake of Allah, He gives you something better in return. It is His promise, and His promise is always true. It really helps to think that we will be blessed by Allah Azzawajal's own Presence! SubhanAllah.. and we will be with our beloved Nabi! In sha Allah ta'ala. It is truly better than anything we could ever think of or ask for. If we have that, it's really all we need. As for the relationships of this dunya, they are our trial, and ultimately Jannah is our goal, no matter what we have to sacrifice to get there. I hope this could give you some comfort, sister. And Allah knows best.