Make sure they know they’re number 1. If they’re not, get your relationship in a better place, or find someone else. Couples therapy can help; so can match.com.
If they are number 1 indeed, the rest is easy. Reassure them, make time for them, and remind them how they are the most important part of your life.
We all need reminders from time to time.
Put your relationship first, make sure your partner knows they’re number 1, and unless you’re doing something they morally or ethically disapprove of, my bet is that they’ll back you no matter what.
Cheers to your best relationship,