How do you deal with libido jealousy?

My(24m) partner(23m) have been talking for 3 months and went on several dates. I met her mother and we kiss quite often when we go out. We also text every day. We meet once a week. We had sex once, but she has sex weekly with her other partner. We do talk quite openly about her partners and what we do with them. I don't care that she does, but she isn't horny when it comes to us doing it. Any advice?

Edit: modified it with FAQ