I'm in the same situation. His parents knew about us and his mom didn't like me so even though we're back together now he doesn't tell his parents.
We broke up twice and got back together again. The first time was because we argue and he couldn't deal with it so he just went away instead of talking it through. After he went away for two weeks and came back all fine as if nothing happened, I found out one month later that he actually went to a female friend house and went in her bed and kissed her but nothing happened- thats what the girl told me. I forgave him because he said its because I made him really angry and he didn't know what to do.
A couple of months ago, we broke up again because his mom didn't want us together so we decided to break up for two months and then he came back to me again. I found out during those two months that he went off and had couple of ONS but he didn't enjoy it- he said he only enjoyed it physically and that he prefers what he has with me which is something more of an emotional connection so that's why he came back. Since he's come back, he's made a bit more of an effort such as taking me out and buying me cute things to make me happy, but even though I don't feel attracted to him physically anymore. I feel like he gave himself away so easily and made him so easily accessible that he is not valuable to me physically anymore, I only want the emotional connection we have, nothing physically. I'm struggling with telling him this as a week ago he asked me 'aren't you attracted to me anymore?' and i said 'yes of course' but I'm not.