He wasn't in love with Claire.

Also, she didn't ground him or make him cook with ion or anything like that. He was escaping with her. Hiding. She was a distraction. And she was more like anaesthesia to him, numbing but not healing.

The relationship also put him in mental crises because why was he having multiple panic attacks while he was with her?

Yes it was quite worrying how she's was fine with her friend hooking up with the next guy at that party because she didn't want to have to call it a night with Carmy. Also, notice that her friend stayed with her through the night during her own "heartbreak" even though she met Fak that night?