The caulk That surrounds my bathtub and the shower keeps pulling away

When you remove three old caulking you must make sure you clean the surface before you recaulk.

One old caulk is of clean the surface well with a non acetone nail polish remover. It will take off the old residue.

Then when you apply the new make one continuous bead of caulking, the moisten your finger and in a continuous motion drag your finger along to create the seal between the wall and tub.

Most important is making sure your surface is thoroughly clean before recaulking.

Clean the heck out of the area and sanitize with a Clorox spray. Waiting until the area is completely dry and fill with a silicone caulk. Then let it dry thoroughly. If the gap/expansion joint is large do a few layers to surround the back letting it shrink and dry a bit between layers.

Mold and trapping dampness of any (even from an exterior wall) keep caulk from holding up. These tips may help, yet some tubs just need to be recaulked every year or two.

Also, I have read to fill the tub with water before you caulk. Sometimes it is the extra weight from a person or bath water that causes it to pull away.

Use a stretchable caulk. Won't leave gaps! : ) http://www.sashco.com/products/big-stretch/

Recaulk😎

Buy some trim tiles, the ones that are about 1/2 inch high with a bull nose if you can find them. Caulk them in place on the "wet" side of the shower enclosure to cover the gap. And definitely fill the tub with water, let it sit until the caulk cures IF you don't have small children around.