I had a girlfriend in university that my friend told me to put through a loyalty test.

I had a girlfriend in university that my friend told me to put through a loyalty test. My girlfriend and I had just started dating. We were 4 months into the relationship. You know how the early days of a relationship are always like. Whenever boys came to meet her to talk to her or ask for her contact, she'd tell them she has a boyfriend. She was so bold about it. She would say things like "even if the school's richest guy asks me out, I'll still choose my man." I used to feel on top of the world. One day, I was having a conversation with my friend about random things and somehow the conversation shifted to relationships and how people cheat on their partners and stories that we've heard. Next thing my friend said was "even your girlfriend, you no fit trust her". I felt offended, because I have had no reason to doubt her, why are you planting that thought and why are you making my girlfriend seem like a bad person. He saw the shift in my mood and immediately apologized saying that he didn't intend for it to hurt me, he just said it based on the discussion we have been having. But that question stuck with me for days, what if he's right? What if there's another guy? I had to ask my friend what he suggest that I do. He said I should put her through a loyalty test, that I should allow him text her through an anonymous account so she won't know he's the one and that he would talk to her like a random guy. If she tell for it, she isn't the loyal kind, if she doesn't, then it's only me. I agreed foolishly. My friend started texting her. He would give me details of their conversations, sometimes even give me his phone to read it. The conversation was very casual, nothing weird was happening. She wasn't doing too much, she was just responding like he was someone random. He was only building the foundation here. I started to wonder why my girlfriend was allowing the conversation run for weeks, shouldn't she have stopped responding? Fun fact too o, she didn't tell me about this "random guy" that texted her. My friend graduated from laying the foundation to actually doing what we agreed on and it was here I started noticing his withdrawal. He wasn't telling me details again, when I asked he would be like "me I don see another shima wey I dey follow talk, your babe no dey answer me". This was supposed to make me feel relaxed that oh, my girlfriend isn't cheating on me but no, it even made me see the possibility more because why isn't he giving me the phone to read it or why isn't he at least, telling me what their conversation is like. My girlfriend on the other hand too started withdrawing but she could easily blame it on school. Things started getting worse when my girlfriend wouldn't talk with me for some certain long hours and my friend won't be around for those times too then when he came back in, my girlfriend would just be responding to my text. This made me suspect that she was probably with him. I had to start asking her questions and she would immediately get defensive and angry. It was beginning to resemble the pattern of cheating stories that I used to hear. Months passed and it got worse, my friend on the other hand moved out of the apartment. The two of them withdrew from me and I didn't want to give the girlfriend title to someone who wasn't acting like it, so one morning I told her that we needed to talk. Oh, she refused seeing me or talking on phone because she was busy and said I should text.