The phone thing is a tricky one. I think I would opt for the assumption at this point that he would prefer you not get in touch with him while he is on a date of any kind. I think by continuing to contact him that you are verging on "bugging" him and distracting him from who he is with. Would you want his undivided attention if you were with him? I would think so... so give this woman that also.
If she doesn't know about you then that can be established later and discussed in terms of whether or not you are okay with that. You could also talk about some boundaries around what you need from him before and after he has a date in order for you to feel that he is not abandoning you and does care.
This is a learning curve, so figuring out how to go about it better next time is a possible solution to make sure it is more comfortable for everyone.
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