Does it eventually get better or vagina adjusts when using a strap on dildo for the first time?

I have not used a dildo before as i have been very satisfied with the "all natural" lesbian sex she can put 3 fingers inside and when she pushes it inside as much as she can its just enough for me. if put in inches..I say she puts them in 4 to 4.5 inches deep.

But my GF wanted to use a strap on on me and we agreed to buy one. Its 6 inches since we searched that this is the average length a vagina can take and when she inserts the whole thing inside, its hurts. The width of the didlo fits me okay. Its the length that bothers me. It hurs inside like i feel that my vagina will rip inside me. She loves me on top (cowgirl) and it hurts a lot more when Im on top as I feel my vagina will burst inside and that its too long.

Not sure if its because I wasn't really ready for it yet or what but will my vaginas depth adjust to the 6inches length of a dildo?

Does anyone else had an experience like this?