First, let me say I'm sorry for my poor English. This is not my mother tongue, but in my country we have nothing like this site to help Christians. I'll do my best. I hope it'll be understandable. I have been a Christian for about 10 years. I'm 22.
I kept myself pure sexually because I know that God wants me to do so. I've had two relationships before. Both of them were with Christians as well, so we were strong and did not have sex. Therefore, when we knew that the relationship was not for our benefit, we were able to step out of it.
This spring I led my friend to God. I met her at the University. She became a Christian, and I knew that she was the answer to my prayers. She was the one that God sent into my life. She was exactly the girl I prayed for. We got into a relationship. Everything was going really good. We felt the blessings of God.
But since we spend a lot of time apart from each other because personal activities, we've decided that we spend a week together. That's what we shouldn't have done. Until this trip, we were able to stop whenever we felt that God wanted us to stop. But on the trip we got into it deep. We went too far. We didn't have sex in the way where you have intercourse. It was "just" hand jobs. After that, we were unable to resist to it. Unfortunately, we went even further, we did oral sex, but for just a moment. We didn't do it until orgasm.
Although that's the farthest we went in a sexual way, we know precisely that it was a huge mistake. We know that we sinned, and we do not want to continue this behavior. The thing is, since we sinned our relationship got "poisoned." We fight a lot, and it's full of ups and downs, mostly downs. I know that this girl is from God. He put her into my life because I prayed for her. I just know it's true. But I also know, that God's blessings are conditional, and those conditions are to follow Him in every action in our lives. I know that we did really bad, and did not follow God's lead on this.
The question is this: how can we renew our relationship in God? We both know that we can't continue doing what we did. That makes it sound almost trivial. But not committing sin again does not change the fact that we have sinned. How can we save our relationship with God? I want to spend the rest of my life with this girl, but now I feel like I will lose her because of what we did. And I don't want to lose her.
I hope I wrote this letter well enough so you can understand my situation. I hope that you will write me back because I need help so badly! Thank you so much!
I suspect that while you had been committed to remaining sexually pure, you became partly dependent on the girl you were with to warn you when you were going too far. With your current girlfriend, she wasn't able to provide that restraint because she was new to the concepts of Christianity and she saw you as the strong Christian. She expected you to keep the relationship pure and you proved yourself weak during that trip.
You didn't say how you ended up in these sinful situations, but I would guess that you allowed yourselves to be alone in each others room. The privacy along with two of you being comfortable with each other allowed you to do things you would not have done in public.
In regards to your relationship with God, you need to go to God in prayer admitting what you did wrong.
"If we say that we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. If we say that we have not sinned, we make Him a liar, and His word is not in us. My little children, these things I write to you, so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous" (I John 1:8-2:1).
Along with the admission, you need to change both your attitude toward what you did as well as your behavior. "For godly sorrow produces repentance leading to salvation, not to be regretted; but the sorrow of the world produces death. For observe this very thing, that you sorrowed in a godly manner: What diligence it produced in you, what clearing of yourselves, what indignation, what fear, what vehement desire, what zeal, what vindication! In all things you proved yourselves to be clear in this matter" (II Corinthians 7:10-11).
Because you treated her poorly, you need to specifically apologize for not treating her with the respect and dignity she deserved. Whether she apologizes in return doesn't matter. Your job as the man in this relationship is to protect her from harm, and that includes protecting her from yourself.
I'm assuming it is the stress about what happened that is causing the arguments in other areas. What I don't know is whether she thought she was showing you love by giving you a hand-job or oral sex. It is possible that she sees your rejection of it as a rejection of her love. Either that or she blames you for using her and bringing sin back into her life.
What I would like you to do is read How much sexual stuff is too much? and What are some boundaries and ground rules couples should have? to learn why your behavior was wrong and why you went too far. Then I want you discuss those rules with her. Hopefully she will find them acceptable.