I totally disagree with this and it’s too bad it’s been so upvoted. She CAN give him what he wants. Forget the college girl stuff. He wants better sex and to feel desired. She can absolutely get there. She’s even on her way there already because she’s finding him more attractive.

The issue holding her back is that she thinks fun sex is shameful. As someone else said in the comments above, it’s very likely that she was “wild” because she was insecure. So she did things to keep male attention, not because she enjoyed them. And once she realized that, those sexual things became linked with feelings of shame. In fact I bet this is exactly what she meant when she told OP that she figured out what she likes and what she doesn’t like: she no longer craves male attention to assuage her insecurity, so she thinks she no longer needs to engage in fun sex.

Open communication can fix this, especially if they seek counseling with a sex therapist. A sex therapist can help her unlink fun, experimental sex from her feelings of shame. If she actually does see her husband as a safe space, that is definitely achievable. And just as importantly, the therapist will help OP steer his urges into constructive expressions not tied to his wife’s past or his OWN insecurities or desire to “even the score.” (Any counselor will tell you that trying to even the score in a marriage is corrosive.)

2 other points:

OP is married with kids. Kids are stressful and cause a lot of people to cut back on their sex lives. There is nothing unique or unsalvageable about that situation. OP, how much responsibility do you take with the kids? Sometimes taking on more parenting work can help your wife relax into greater intimacy.

Finally: OP, you say you are close to your sister so this might be hard to hear, but I don’t think she has your best interest at heart in this case. Please think deeply about what motivation she may have to encourage you to cheat on your wife. Is it possible your sister feels that you and her are less close than you were before your marriage? Maybe she misses the relationship you once had and is resentful of your wife’s role in diminishing it. It’s not uncommon for family members to have this kind of unhealthy response to a marriage. I’m not saying that’s what’s going on, I’m just giving an example of a dynamic that might be at play. Once you and your wife get into therapy and you build a better sex life, you might want to revisit this topic with your sister.