She may actually be happy with how much time she spends with him. However, if you get the sense that she's not, encourage him to speak with her. She will likely feel a lot more comfortabe telling him her needs than you. Let him negotiate it and be open to possibly losing time with him to allow her more. Don't assume she needs the same things you need though. Everybody is different. Just keep being empathetic and willing to work with him to allow their relationship to grow.
Me - Mostly mono female, 39 yrs old, married to Leo.
Leo - Poly bi-sexual male, 37 years old. Married to me and looking.