[32F] [32M] My fiancé is having difficulty maintaining an erection.

Hello. I’ve been in a relationship with him since 2018. We met when we were both 25. He told me I was the first girl to give him a chance and that he was a virgin, while I wasn't. During our first sexual encounter, he struggled to maintain an erection, which I assumed was normal for a first time. After a few tries on different nights, he was able to perform well and would even last around two hours with breaks in between. The first year was wonderful, but things changed when I became pregnant. Our sex life remained good for another year, but I later discovered that he was flirting with other women online. I wasn’t heartbroken, but once I noticed this, our intimacy felt different. Sometimes he couldn't get hard at all, and other times he would only last a minute, despite wanting to be intimate. I found this perplexing, and it went on for months. When I expressed my feelings, he assured me he was still attracted to me but didn’t know what was wrong. Now, four years later, since 2020, he still faces difficulties with achieving and maintaining an erection. Occasionally, he would manage to get hard, but most of the time, he was soft. We had another child as well. Over the past year, I noticed that he stopped initiating sex, which frustrated me. When I brought it up, he started asking for sex again, but every time we were intimate, he struggled to get hard, and when he did, it was only semi-hard. Today, during what was supposed to be sex, he pretended to ejaculate, and I suspected he was lying since I didn't see any evidence. He claimed it was just a little bit. Nowadays, he only becomes fully hard with foreplay and has normal ejaculation, which was not an issue in the past. This was the first time I felt he lied to me. I confronted him about it, expressing my frustration and asking whether he still found me sexually attractive. He insisted he did, but his actions have led me to question that. He claims he doesn't understand why this is happening. After being patient for four years, I’m considering ending the relationship. I worry about our children and how they might feel if we separate, but it's becoming unbearable for me. Am I making the right choice? What could be causing his issues?