We cannot "fix" our spouses. To do so, we would need to assume the "better person" role and pronounce as flawed the person we vowed to love and honor, revealing disrespect. Not a good idea in a relationship based on respect and sharing.
The best we can hope for is to influence our spouses, to hope they will admire our choices and adopt them as their own. Short of that, we can hope to find a Third Alternative to our competing preferences.
So, if waiting for your spouse to show up keeps ruining your mood, here are some Third Alternative suggestions for you.
To you, "on time" might mean five minutes to five seconds before the agreed-upon time. You're not wrong. To many, including airport personnel or officious maitre d's, this is exactly what it means. But if you married someone who almost always shows up for lunch or dinner or an outing together 15 to 20 minutes later, you're not listening very well.
You're both consistent, and you consistently hear something that ticks you off and makes you less pleasant to be around, when your husband or wife never intends for you to show up when you do. In fact, you could probably show up 30 minutes after the time you hear and not do as much harm to your relationship as showing up at the time you hear is doing.
If you choose to show up earlier than your spouse, instead of rehearsing your fears that the most important person in your life doesn't value you or your time, or worrying about the calamities that would have to occur for you to be late, you could think about the things that make people like your spouse consistently late.
Like optimism. If you value your wife's or husband's optimism at other times, why not enjoy it now, when traffic or dressing the kids or picking up the dry cleaning is going a lot slower than an optimist predicts?
Or presence. If you were lucky enough to marry someone who is fully present with you and everyone else in their life, why not think of all those wonderful moments as they fail to hustle away from someone to make it to an appointment with you?
Or flow, that total, immersive engagement in life's attainable challenges. Don't you love that look in your mate's eyes while in flow and that full-face grin as they emerge from it? If that's what just delayed his or her departure, do you really want to meet it with scorn?
Your spouse can't "fix" your promptness that turns into corrosive resentment, but perhaps you can choose to take another look at what he or she gains by being less prompt.
And if you're the spouse who usually arrives second, you too can adjust what you hear. Just subtract the typical difference and proceed as you would with the later time. When you arrive, if you sense anger or disrespect, don't apologize or focus on what was happening to you. You've surely noticed it doesn't really help. Instead, thank your spouse for waiting for you. Ask what you can do to make your meal or outing go better now that you're here.
Because both of you are right. You just don't agree on which variety of "right" will work best in your relationship. Let yourself be inspired. Find that way that works for both of you.