Why does he want try sex this way instead all of a sudden? /u/No-Trainer2416 Sex

I was sexting my bf (M28) pictures and he always request more pictures of my butt. I (F27) have a rather shapely backside that he’s always given attention to as well as previous partners. Everytime we are intimate he gives my other body parts attention too by licking or kissing and showing lots of affection to me like he enjoys it. But during our sexting he said he wanted to lick and do backside sex to me which was very new to me. I’ve never been shy about pleasing him nor has he been shy about pleasing me but it’s always been tradition sex/ oral. I’m confused because this is first time expressing this to me . Also he never last long when we have sex the traditional way (like 10 mins or less no exaggeration) and always tells me how good it is. He also said he’s done backside things to woman before like often. He’s my 3rd bf that’s said he wants to try this with me but none of the others have ever done it and neither have I. Should I be concerned on my bf just telling me he’s done this and wants to do it to me now after a year of dating? Could my bum shape have something to do with men’s desire to want to try it with me? Was this just a horny outburst like the others? Backside sex is also more taboo in our culture for some reason atleast in my mind. I don’t want to shame him I just am confused on his sudden request?

I was sexting my bf (M28) pictures and he always request more pictures of my butt. I (F27) have a rather shapely backside that he’s always given attention to as well as previous partners. Everytime we are intimate he gives my other body parts attention too by licking or kissing and showing lots of affection to me like he enjoys it. But during our sexting he said he wanted to lick and do backside sex to me which was very new to me. I’ve never been shy about pleasing him nor has he been shy about pleasing me but it’s always been tradition sex/ oral. I’m confused because this is first time expressing this to me . Also he never last long when we have sex the traditional way (like 10 mins or less no exaggeration) and always tells me how good it is. He also said he’s done backside things to woman before like often. He’s my 3rd bf that’s said he wants to try this with me but none of the others have ever done it and neither have I. Should I be concerned on my bf just telling me he’s done this and wants to do it to me now after a year of dating? Could my bum shape have something to do with men’s desire to want to try it with me? Was this just a horny outburst like the others? Backside sex is also more taboo in our culture for some reason atleast in my mind. I don’t want to shame him I just am confused on his sudden request?