Has it always been like this or is a recent thing?
This is probably something you're not going to want to hear but it's possible you're not very good at pleasing her. This sounds way harsher than I mean it to so please don't think I'm attacking you! When my current boyfriend and I started having sex, he wasn't very good at understanding what I enjoyed and I was too insecure/scared to tell him. This wasn't his fault of course, I just wasn't very good at communicating about that stuff and I wasn't entirely sure what I liked either being inexperienced. This lasted for a couple months until eventually he got frustrated and we had a long conversation about it. Once I realised how much he wanted to please me and that he didn't enjoy sex if I wasn't enjoying it, it became a lot easier to talk to him about that stuff.
Essentially, my point is not to insult your sexual style but rather to suggest that your wife might not feel comfortable talking to you about what she likes. It could be any number of things really so I would suggest just talking to her and making sure you don't phrase it in a way which makes it seem like you're attacking her. For example, asking in a suitable moment 'is everything okay with our sex life?' might work wonders. My boyfriend is reluctant to talk about sex so I asked him when we were about to go to sleep in the dark and I think the lack of lights made him open up a lot more than he would have otherwise.
Apart from that, all I can say is be intimate with her. Not sexually but emotionally. The moments I want my boyfriend the most are the moments when he's not trying to have sex with me but instead does something to prove he cares about me as a person. Emotional intimacy will lead to sexual intimacy with time