Last month, my partner (now XP) left me for someone else. We have lived together for 7.5 years, but we are not married. XP will soon find a new place to live for both herself and her daughter (SD). SD is 11 and I have been a parent to her since she was 3.5 years old. SD and I have a very close bond and, out of the adults in her life, I am the one with whom she spends the most time. During the week, I am responsible for most of the standard parental tasks (meals, school, activities, bedtime), and we often chat and play games together. When speaking to third-parties, SD will refer to me as her "dad" and she considers herself to be my daughter. I feel the same way about her. SD is the most important person in my life.
My concern, now that XP has broken up with me, is that I have no parental rights in relation to SD (I'm in the UK). Therefore, AFAIK, my continued involvement in SD's life will depend on XP's consent. SD wants to live with me part of the time during the week and be able to see me (or stay with me) on some weekends.
XP was initially in favour of sharing parental responsibilities with me on a flexible 50:50 basis. XP suggested that we have a schedule of one week on followed by one week off, depending on our work schedules and other commitments. I would be thrilled to have this arrangement. I desperately want to remain a parent to SD.
Unfortunately, in the few weeks since the break-up, XP has become non-committal about my involvement in SD's life. XP has told me that it depends on logistical factors relating to where she will be living (she's still looking for a place). This cooling-off has coincided with XP spending almost all of her free time elsewhere, presumably with her new boyfriend, leaving SD at home with me. When I asked XP if she plans to move in with her new boyfriend she was very dismissive of the idea, but that was a couple of weeks ago. AFAIK XP has not told SD about the new boyfriend, but SD knows that XP has overnight visits with someone.
Based on XP's reluctance to talk about co-parenting, it feels like XP is planning to form a family unit with the new boyfriend and that I am possibly facilitating that by looking after SD whilst XP is out. A new family unit would leave no space for me in SD's life because she still sees her biological dad every other weekend. However, I don't know anything about the new boyfriend. So I have no idea if he would be interested in being SD's parent.
I will continue to be SD's loving and supportive parent until she or XP say that I am no longer welcome in SD's life. What I would like to know from the other members of this community is whether you have any suggestions on how I could improve my chances of convincing XP that I should remain a part of SD's regular everyday life? Perhaps other step-parents have been in a similar situation and managed to persuade their XP to agree to a co-parenting arrangement?