This is a very valid issue, and a fairly common one: huge change in personal and professional circumstances, new phase in life too. You're very lucky both environments are very positive, you're not hurting for love/companionship nor for money.
Still you've got to start building the next phase and it can be hard, both because what you want has evolved, and because what you want no longer is the only objective to take into account: the wife and maybe kids also have a voice, directly or indirectly as an impact on your own priorities.
This is a complex, ongoing challenge that won't be solved by one, or a hundred, HN comments. So the most important thing is to start and maintain discussions about it, with yourself (set aside quiet times, start a journal...), and with your wife, and with trusted friends/family, and probably indeed with a therapist - don't be shy about shopping around until you find one you gel with.
Volunteering or working in a job with an altruistic impact can be it for some. Or more professional / financial progression. Or free time for family / hobbies. Or a relaxed work atmosphere (or on the contrary stress)... If you feel stressed/depressed, a pet is both a relaxing distraction and an unconditional source of love (esp. dogs birds and horses, cats are iffy !).
Don't be afraid of a temporary void, but don't wallow in it either.