1. I forgot.
2. I’m in a hurry
3. I’m really busy
4. He’s been a brat.
5. It would be fake affection
6. She already knows I love her
7. I showed him affection yesterday
8. I’m not feeling affectionate right now.
9. She doesn’t deserve affection right now.
10. He hasn’t been very affectionate towards me lately.
11. She’s independent enough that she doesn’t need it.
12. My last attempt at showing love was not appreciated.

I suppose you could put most or all of these under the title “Bad Reasons for not showing love to anyone.”

* And by “love/affection” I mean words of affirmation and encouragement, hugs, pats on the back and gifts. Also acts of Grace and Mercy. And Training and Discipline.