Thank you yellowDahlia you have absolutely nailed it (again!) and I could have written both of your latest posts! 
I have found the pandemic hard work, and although DH has had to work flat out too, he has enjoyed wfh although he is feeling more cooped up now. We've had too much unrelenting non-quality time together and the stress the teens have been through has not helped. As you say, our relationship definitely needs some time to breathe!
To answer questions from other posters, no I don't want to end my relationship, I still love my DH, and our sex life is still good, if a little restrained currently by having teens in the house.
The problem is definitely as yellowDahlia has defined it. It's a mixture of the pandemic, my age (mid-fifties), one of the teens leaving home, a close friend becoming seriously ill with cancer and therefore a sense that if I am going to do something for myself, I need to do it now!
Am I destined to always live in the same house, because that's what he wants, or never to own a cat because he hates them, or will I ever get the chance to travel somewhere alone (for fun instead of work) because he would feel snubbed? I'm not one of those wives who can just go off and do something no matter what their partner thinks, I'm a people pleaser and I'd feel too guilty
^^This part of yellowDahlia's post definitely rings true! As she said earlier, the little compromises add up. My personality is such that I feel guilty too if I go and simply please myself but it is important to understand it is all a balancing act. If I get too demoralised or depressed it doesn't help my family either. It's working out where the dividing line is I suppose.
And as you say,
I guess these things are ultimately not the most important things - having a happy, healthy family is more meaningful than those and I am grateful that we have the life we have. It doesn't stop you feeling a bit sad for what you give up though, and I think that's probably normal and natural and worth considering instead of bottling up.
^^Yes this is definitely worth considering, within the context of being grateful for the important things. Thank you! 