My girlfriend and I have been together for six months. We have a past as well. We are both believers in the Lord and have been for a while. We both have children from past relationships, prior to becoming believers. We are currently struggling with our relationship, in part because we both have backsliding issues we are dealing with. We don't live together, but we do live very close to each other. We both have been doing things of the flesh -- physically and emotionally. She is also going through some struggles with addiction to drinking and smoking, and I am not innocent of the drinking either. She is trying to quit smoking and get back into faith with the Lord through prayer and guidance. I'm struggling with this because for the first several months we spent a lot of time together and did a lot of things together. Now she is pulling back and wants time to herself. She says she is doing this to get back in the Word, and I completely back her up 100% on wanting to do this. I have a hard time with the distance between us now, and I have been struggling with bad thoughts regarding what she is really doing. My mind has been getting the best of me and, in turn, causing problems with our relationship.
Any suggestions on this will be greatly appreciated. Feel free to ask any questions.
I generally have difficulty when someone writes telling me about their belief and commitment to God while explaining their disobedience to God during the same time period. It is this type of attitude that got Jesus so upset with the Jews. "You hypocrites! Isaiah was right when he prophesied about you: 'These people honor me with their lips, but their hearts are far from me. They worship me in vain; their teachings are but rules taught by men'" (Matthew 15:7-9). The word "hypocrite" means an actor -- he is playing a role, but it is not who he truly is.
I'm glad you are interested in improving, but let's not dress up the past. You and your girlfriend have been involved in fornication with other people for a while and that has led to both of having children. I am assuming that by saying "relationships" neither of you has been married before. While you both became believers in the Lord, this belief did not cause either of you to really change your behavior (i.e. there really haven't been many signs of repentance). You and she have been involved in drinking, lust, lewdness, and perhaps even fornication since becoming believers. "Now the deeds of the flesh are evident, which are: immorality, impurity, sensuality, idolatry, sorcery, enmities, strife, jealousy, outbursts of anger, disputes, dissensions, factions, envying, drunkenness, carousing, and things like these, of which I forewarn you, just as I have forewarned you, that those who practice such things will not inherit the kingdom of God" (Galatians 5:19-21).
It sounds like your girlfriend realizes that she can't be partially committed to Jesus, and she is working on improving her relationship with Christ. This is a guess, but I suspect that she is distancing herself from you because she sees you as a pull back into the world. She is fearful that being with you will lead her back into doing things that are contrary to the teachings of Christ.
While you are happy that she wants to get closer to Christ, and you know that you should get closer too; yet, at the same time, because she is no longer being intimate with you as she was in the past, you are fearful that she no longer loves you and that you might lose her. Your fears have caused you to be suspicious of her and that has led to fights, which are not helping matters.
Since you know that your behaviors of the past are wrong, the first order of business should be to get your life completely on track. "Why do you look at the speck that is in your brother's eye, but do not notice the log that is in your own eye? Or how can you say to your brother, 'Let me take the speck out of your eye,' and behold, the log is in your own eye? You hypocrite, first take the log out of your own eye, and then you will see clearly to take the speck out of your brother's eye" (Matthew 7:3-5). With your life on track, then you can reach out and help her with some of the issues she is struggling with. Rather than being the source of each other's weaknesses and failings, you can both be each other's strengths.