Being a male nurse is actually pretty good

I’m 35M, been with my gf 3yrs, we’re talking marriage soon. We both have 2 kids from previous relationships, both kids are with their dads, mine is a doctor. I work 40hrs a week as a nurse anesthetist. I’m also in school pursuing my PhD. I’m a great dad and bf, very attractive, work hard, and I’m doing well financially.<br><br>I’ve been noticing that I get more attention from single moms than any other man. I was at a pool with my kids yesterday, and there was a single mom with her 2 boys, 4 & 1, they were playing in the kiddie pool. I brought my kids over and we all started playing together, and it was clear the boys were having a blast with mine. I went to get some snacks for the boys and the mom and sat together. She told me she was 25, and her husband cheated and they broke up. I was nice to her, but nothing too flirtatious. She asked what I do, and I told her. She asked what kind of doctor, and I told her nurse anesthetist, and she said oh. But through the whole conversation she kept complimenting me, like saying how nice my biceps look, how great of a dad I am, etc. Then I got up and got some more snacks for everyone and kept playing with my kids. Then she said “wow you’re a great dad, you’re so good with my boys. Do you have any kids?”. I told her I had two and she got quiet. She asked what my schedule was like, I told her 40hrs, and she asked if I was interested in hanging out sometime. I told her I was in a serious relationship and I didn’t have time for anything like that. She was a bit sad, but said thanks for hanging out with her and the boys, and I said no problem at all. I picked up my kids and on the car ride home, my gf texted me “what’s going on?” and I told her the story. She’s furious, and told me to never do anything like that again. I said I didn’t, and she asked why the girl thought I had no kids if I told her I did. I said I didn’t say she had my kids, just that I had two and they’re with their dad. She said I shouldn’t have been hanging out with a single mom if I was in a serious relationship.<br><br>I’m confused. Is it that bad of a thing that I’m single? Is it wrong for me to be friendly with a single mom? Should I have lied and told her I had no kids so that she’d leave me alone?