It really comes down to making a decision about your values and priorities. Ie, if you truly value your significant other, then give them your valuable time. If you are good about honoring work appointments, treat it like an appointment with your spouse and honor that commitment.
Also, give your significant other the BEST part of your day. If you are sleepy in the evening, make sure you focus time and attention earlier in the day so your spouse isn’t getting your leftovers.