Overpromising then underdelivering/forgetting?

Is this a common thing you've experienced with your pwBPD?

Every single person I've met with BPD will make these big sweeping (often unpromppted) promises (at various stages of the relationship) and will almost never deliver. Not only will they not follow through, but they'll never come close. Almost as if they fully forget they made such a promise - and will become dismissive/vitriolic when it's brought up.

Examples can include something as small as say suggesting sex in the morning/later, or making plans to hang out (Only to act like they never did). Or something a little more difficult to ignore say promises to buy certain things you need/gifts, make/order food, or take care of you/drive you home after a medical procedure.

Is this common? Is this a part of love bombing even if it's later in the stage of the relationship?Why does this occur?