feeling 'trapped' in monogamy.

feeling 'trapped' in monogamy.
so i've(20m) have been in this wonderful relationship with A(20f) for about a year now, and as I disclosed from the begginging that I was looking for a open/poly relationship, she knew it from the very start and we agreed to that. Fast forward a couple of months and we close down the relationship because she doesnt feel secure enough, which was also a completely valid request. After we opened it back up she went on a date with someone, made out and then proceeded to tell me that this is not something she wants to go look around for, after that we closed the relationship again. Since then neither her nor me have been on any dates and any discussion even hinting towards the topic elicits an we should try it at a different stage of our relationship when we are more secure. This makes me feel trapped and controlled, especially since she knew about me wanting a non-exclusive relationship from the start. Any advice?