Do you have family or a close friend who may be able to take care of your absol now and then? Although this seems a little less than ideal (separating yourself from your partner, that is), think of it like allowing a close friend or family member to babysit a child for a day. So long as you instruct your absol to listen to her temporary caretaker and ensure that said caretaker knows how to handle your absol, letting her go on daytrips as often as possible may be enough to alleviate the restlessness that she feels.
If, however, you don’t have a trusted friend or family member, you may be able to find a trainer who specializes in “babysitting” pokémon. Alternatively, your only other option may be to reassure your absol that this change is only temporary and that when the baby is old enough, you will not only be able to resume your adventures, but you will also do it with a new companion (so long as the adventures in question aren’t dangerous for a small child).
Best of luck, and congratulations, anonymous!