Inexperienced buck? Non receptive doe? They won’t frick

I’ve been putting my VERY willing buck in with an experienced female that I bought and the guy I got her from said she’s about a year- year and a half old and she’d had a litter about a month prior to buying her. My buck is almost 4 months old which I think may be the issue- but by god does he try. He tries so hard and just can’t get it in. He’s had two fall offs in total but I’ve had them together at least seven times. He just tries his best but just can’t do it right, and I’m starting to get suspicious that she’s clamping her bunny legs shut or something.

Any tips? Mood lighting? Rose petals? Doing the dishes without being asked? If the answer is “he’s just too young” I completely understand