PLEASE don't put them together
at all. It only takes a second for him to mount and get her pregnant. And if they're joined it is dangerous to try and separate as you can cause damage to both, the boar in particular. You both need to get them a same sex friend each, preferably from a rescue where they can be dated to pick one they like.
As for being in season, it's generally more noticeable when they live with a companion. If she lives alone you won't know because...well... you're not a guinea pig so she won't behave the same with you as she would a friend.