Even though his contact was erratic at times, he messed them about being late and he always put himself first, married without telling them etc., they haven't stopped seeing him.
Things were a little easier when he didn't have to pick them up, but could pay for a coach ride for them, to him.(I wasn't keen, but kept out of it, I felt it lacked care) . They were also easier when they got their own phones and could manage their own contact, without me.
They are young adults now. They know what their dad is about.
They love their dad. In fact, one has moved closer to him.
Relationships are important, they have a measured approach which I support, but keep out of.