We just past our 5th anniversary last a week ago. It's been a happy for the past "4" years, we were like a couple. Everything changed when she met some friends who love to go clubbing. Last June, she told me she would like to go clubbing with some of her newly met female friends. At first I thought, giving her some girls nights wouldn't be a bad idea, so I gave her my support to go have fun with them. After that first clubbing night, her personality started to change. She started to wear very sexy and doing very strong makeup (her excuse was guys only go for girls that were like "girls next door" who didn't wear sexy and didn't wear lots of makeup in clubbing). Then from going clubbing once a month to twice a month, then once a week to twice a week. Eventually her cellphone rang alot more than before and always she just looked at it and "ignore" it when I'm around. I was so naive at that time that I trusted every single word that she said 100% and I really did trust her 100% without question. Last August, one of my friends suddenly told me "I have seen your girl friend hugging and holding hands with a guy who is not you.." I was shocked but I need to "feel" it myself if it's true or not so I acted as if nothing happened. I paid more attension on her unintensional "moves"~~~ I even gave her little hints that I knew something's going on and she better tell me straight forward. A month passed, I finally couldn't stand it anymore. But then she said her period was 2 weeks late, so I wanted to know if she's having a baby or not then I would decide if I should confront her or not. Eventually we found out it's negative, so on that night I confronted her about the issue, I told her I knew she's seeing another guy behind my back. At first she still stood her ground saying "HELL NO", then I told her someone saw her with another guy as if he's her bf in a mall... Then she cried and said yes... she told me she met that guy in a club and she saw him as a "toy" because he's so very handsome and she didn't have any feeling towards him at all. I was mad but I loved her so so very much so I took a deep breath and said I would forgive her if she promised me she wouldn't EVER contact that guy ever again and I would like her to stop going clubbing for at least a month to let her gain me back some trust on her. 2 weeks passed and she told me she's going to have house dinner with her gal friends, I let her go... she even let me see the way she dress and her very light makeup as a "prove" that she's really going to have dinner only. Once again I trusted her, but the next day......I found out that she went to her friend's house to redo her makeup and changed into some other sexy clothings for YET ANOTHER club night. I calmly asked her why she lied to me again? She didn't say a word. I was so disappointed yet once again I LOVE her so much......But after that, we started to communicate more, telling each other things what we wouldn't normally say, and I really did my best to improve myself, so that I could be a better bf in her eyes. 4 months passed, we were talking about getting marry in summer... On early February, her cellphone got cut because there was a mistake made by the cellphone agent who didn't changed her plan to unlimited week nights and weekends, so her phone bill went to $700. Since I was the one who's paying the bill, I went to the online billing to see what's going on. I saw the amount I need to pay and called the cellphone company to see what's wrong, they told me to look into the detail phone call and see if there's some error. To my surprise I saw a phone number which she told me she wouldn't call again (that guy's number)... Eventually the bill is settled. I told her I have seen a phone number that I really didn't like on that bill. She said "Yes I tried to call him but no one answered... I was drunk that night" No appology from her at all... After that she changed the cellphone online bill payment password.. and I knew there's more to it... One day I was at her place browsing with her pc, and by accident, I opened up a text file (when pc was slow and you tried to click something, but the mouse wasn't responding where you wanted to click on). It was a diary of her time with that guy, when I looked at the date, it was a week ago. I was so mad and confronted her again... she cried and I told her I couldn't stand this anymore, then she hanged up. When I calmed down, I thought back our years together, our happy moments together... Then I went to find her and told her I still loved her and please please don't do that to me again. After two weeks, she wrote me an email saying she's sorry, she liked him only because of his apperance nothing more, and once again she would NEVER see him, contact him, call him EVER again. I told her it would take time to heal, and lets put things in the past and lets look forward. In the middle of March, I have found out she's once again seeing him again... Just two weeks ago, she told me her doctor just told her, she has Hepatitis B and because of that I wanted to look after her more.... but I really can't stand her keeps on cheating on me.... What shall I do?