Perhaps you two should never have started a relationship in the first place.
When you met Trafalgar Law, you were already aware of his quirks and his general lack of commitment to people, even those close to him. Still, that didn't stop you from feeling drawn to him and falling for him, especially when he showed some interest in you.
However, you were always stubborn and persistent, maybe even too much of a dreamer and a bit naive — everyone said so, anyway.
The proposal came out of nowhere, in the middle of nowhere, with no one else around, just the two of you. You remember it clearly; your memory never fails when it comes to Law.
"Let's date." was all he said, before going quiet again, putting a cigarette in his mouth, and returning to watching the moonlight in the silence of his apartment balcony.
In the beginning, things were okay, although his constant absence made you sick with anxiety and longing to see him. But then, before you knew it, it was just superficial chats and going to bed. Nothing more. This started making you feel... bad. Exhausted. Used? Yeah, that too.
The last straw was on your anniversary. Law had spent the day at his internship and then went straight to college. You tried to reach him multiple times throughout the day, but you got no replies or callbacks, which hurt you so much that you cried for hours.
And yes, he had forgotten your anniversary.
"I'm home." he said, walking into his apartment, knowing you were there — as always.