Anal sex on him

So my boyfriend is really big into sex he likes it anyway he can get it when it comes to me. But I am new to anal and try to avoid it sometimes I will give in but not often. He has told me before he has tried anal on himself but he was very embarrassed when he did say it I mean very embarrassed. He almost did not tell me and he is not a shy person with me. He has been open with things most people would take to there grave and yet this he is embarrassed. I have ask him if he wanted me to play around back there sometimes and he freezes or panic yells no so I don’t really push. I have tried talking to him about it but he gets nervous and gives short answers. He told me he would not do it again and he has told me he would. He said I am the only person who even know and I respect that no one else needs to know. He had toys but accidentally left them when he moved. We are working on moving him in with me but are waiting until he finishes his college classes to do so as I do not have Internet where I live other the. My phone. So he stays with his parents I offered to keep all toys at my house as I live Aline with my kids but he is really touchy on the topic. I know it’s not a trust thing because we talk about much worse and much more private embarrassing things like they are nothing. What can I do to get a straight answer out of him. Or help with the dilemma. If it’s someone he likes I don’t want him feeling like he needs to hide it we already have plans to get married and I know so many taboo attractions I just don’t understand.