That doesn't sound selfish but like a sensible strategy, it's very frustrating when people let you down like that, especially when we all know how much juggling and planning goes into this running business. She definitely sounds too unreliable as a training partner - as for periods, running is good for period pain and clears the head. Perhaps next time you can say what you're doing and suggest she comes to you if she can make it.
Glad you got up several respectable peaks in Cumbria, yes Sca Fell is always a bit of a logistical pain unless you've got loads of time or two cars. BTW, when you go to Snowdon, were you planning on sticking the rest of the family on the train to the top? If so, bring credit card, daughters' dowries, lottery winnings etc to cover the incredible fare of £16/adult and £13/child return! Now there's an incentive to walk it instead. (or leave recalcitrant family members in cafe with the Sunday papers).
Eventually got out and did 6 sweaty miles with the kids on their bikes, either going slightly too fast for my planned pace, or stopping altogether demanding break, drinks, sympathy for imaginary hurts etc. It's called 'quality time' I believe.