1) Self love is important. Think of yourself first. Have the outlets you need in those tough moments/days - be it talk to a friend or an activity you love

2) Patience and understanding.

3) Communication is important. This is probably a difficult one trying find the right moment and a cater to different situations. But explaining to your partner that unfortunately you can't read their mind and that you understand he has those tough moments and so it is a matter of communicating you are down and need to be alone or that you are around to listen.