I'm a 21-year-old guy, and I have a feeling that my relationship with my 20-year-old girlfriend might be coming to an end soon.

I'm a 21-year-old guy, and I've been in a relationship with my girlfriend, who is 20, for nearly five years—our anniversary is on March 1st, 2025. We've had our share of ups and downs, but I’m writing this because I've made some serious mistakes. I've struggled with liking other girls’ posts and looking at things I shouldn’t behind my girlfriend's back, getting caught multiple times in the process. I know I shouldn’t be the one asking for advice, especially since I’ve hurt her and acted like a total jerk. It’s confusing because I still love her deeply. Back in November 2024, she found out I was liking another girl's posts, and things have felt different between us ever since. She’s started to drift away and is now seeing a guy friend who clearly has feelings for her. I’m aware of this because we still communicate reasonably well. I've sincerely apologized to her and expressed that I don’t want to give up on our relationship; I want to fight to keep our love alive. I was too scared to let her go when I thought it would be best for both of us. Now that I realize she’s the one for me, I want to change and hold on to her. She tells me she feels numb now and doesn’t have feelings for her guy friend, yet she admits she still loves me—after all, it’s hard to dismiss four years together. I’m doing everything I can to win her back; I talk to her, compliment her, take her out on dates, buy her food and flowers. We even slept together recently, but she said it felt wrong. When we're together, I feel like I'm becoming the best friend and boyfriend she needs again. However, when we're apart and I call her, she often seems disinterested and makes excuses to end the conversation. I can’t shake the fear that karma is coming back to haunt me and that she might be moving on, even if she doesn’t recognize it yet. I know I deserve this. What should I do next?