If this morning’s ride time has been agreed with your other half then this morning’s ride should really have happened absent a good reason not to.
If it was your unilateral choice that you were going that’s where you can end up unstuck.
Is Mrs coping OK with the two? They are at that age where that are hard work and two is definitely worse than one (it gets easier once they start playing together). Her reaction could be because she’s frazzled not because she doesn’t care about your leisure time?
Is there any suggestion of pnd?
Are you agreeing leisure/kid free time for both of you? Can you take the initiative and give her a couple of days or afternoons of at the weekend.
Can you take the MTB to work and head off to the trails for a couple of hours without going home in between (90% of my riding)? This works well for us, little impact on family time, it’s predictable and is rarely cancelled for anything other than work reasons.