

As much as my ex pains me when my oldest son in the past would go through his emotional hormonal outbursts in telling either my son or myself to work it out between us, reading this, puts into perspective what that means.
As far as being 19, ironically, that fact brings to memory one night out with my girldfriends and a mutual declaration amongst us, that 19 was that one age we'd all wished never happened. It sucked.
She's really going to need to come to grips that men don't leave because of the kids that a woman has from a previous relationship. That barely touches the surface and it's just too simple of an excuse. It's a mask for an unwillingness to work at the relationship. It's quite similar to being both afraid of commitment and a lack of knowing or wanting to push through the rough edges that relationships face.
Much like your feeling about how your stepdaughter sees you is much like a bigger metaphor of how life has been.
Maybe your daughter subconsciously or consciously feels that way about the totality of her life, thus far. Your older daughter needs to address her own anger.
Life isn't perfect. Upbringings aren't perfect. But darn it all, the desire for some peaceful middle ground is typically universal.