I met this girl in my class, we'd talk here and there, and eventually I asked for her number. We'd mostly talk about goals, God and the Bible. I eventually developed some feelings and wanted to get to know her on a relationship basis because I have always been praying for that. To meet someone where we can base our relationship on God. She made it clear that she wanted to be friends, but her actions would prove otherwise. For example, bringing me lunch to work or getting mad when she thought I was with another girl when I really wasn't.
We were hanging out one day and got close, eventually holding each other. I kissed her. She wasn't mad, but she made me leave her house. Should I apologize? I am not a virgin, but I made the decision to remain celibate. I was not going to cross the line with her. I feel as if I crossed the line, and it has been bothering me. I want to base everything off of God -- friends or relationship wise.
I'm glad you want to do things God's way this time. Your friend seems to be smart in this regard. She understands that sexual feelings can quickly get out of hand; that is why she had you leave.
When a person pushes the limits or pushes things along too quickly, it becomes a warning sign of someone who lacks self-control. Notice that you read more into her feelings for you based on her actions. So what were you saying by your actions, ignoring what you said and what you think? To her, you and she are just friends. There hasn't even been a declaration of boyfriend and girlfriend, and yet you gave her a passionate kiss. These are things a guy who has little restraint would do, so while she likes you, she chose the path of caution.
Another thing to consider. I know you are determined not to have sex. Have you also thought about the things that lead up to sex? God warns against lewdness. Lewdness refers to shameless behavior, particularly in regards to sex. It is behavior that is involved in pure self-enjoyment or behavior characteristic of an animal. So things like foreplay or behavior that arouses your sexual desire would be lewd. "Let us walk properly, as in the day, not in revelry and drunkenness, not in lewdness and lust, not in strife and envy. But put on the Lord Jesus Christ, and make no provision for the flesh, to fulfill its lusts" (Romans 13:13). Lust is thinking about doing something that is wrong and justifying that it would be all right at least in this case. The reason lewdness and lust is forbidden is because they lead up to sex. You don't start something that you can't morally finish.
Solomon points out the problem when he asked, "Can a man take fire to his bosom, and his clothes not be burned?" (Proverbs 6:27). You can show a hot coal all the affection you want. You can cuddle it and dote on it and it will still burn you. Your kindness to it doesn't change its nature. How often do you hear someone say, "But I love her!" Solomon's point is that your feelings toward girl won't change the fact that both of you have built-in desires and capabilities for sex. Trigger them and they follow the instincts built into you.
Solomon also asked, "Can one walk on hot coals, and his feet not be seared?" (Proverbs 6:28). Using the same example of a hot coal, if you walk on it, it will burn you. You can apologize and say you didn't mean to step on it, but you'll still be hurt because your intentions doesn't change what it is. Thus, the excuse, "But I didn't mean for it to go this far!" becomes an empty one because your intentions doesn't change your body's drive.
That is why Solomon concludes, "So is he who goes in to his neighbor's wife; whoever touches her shall not be innocent" (Proverbs 6:29). Though he is talking directly about adultery, the same point is true about fornication. When you start intentionally stirring up sexual feelings, you are never innocent when thing go further than you wanted. This is also why Paul said, "Now concerning the things of which you wrote to me: It is good for a man not to touch a woman" (I Corinthians 7:1). By that he means touching a woman in a sexual way.
In other words, you can't use your past as a guide in this case. Your past lead you to having sex with a girl. To avoid it, you have to treat this girl completely different. It is your job to protect her, even from yourself. "Let no one despise your youth, but be an example to the believers in word, in conduct, in love, in spirit, in faith, in purity" (I Timothy 4:12).