Well of course to SOME men they will be unattractive whether they admit it or not. Just like when questions like these are asked about boob size, weight, hair color, or whatever else about the physical appearance. Everyone has their preferences and some shallow people are picky (men and women). BUT a man worth your time will love you for you and not even think about those things. Stretch marks are pretty common and not such a big deal in my opinion. I had some that faded in time and aren't noticeable now.
Don't feel bad about yourself for something you can't control, focus on your good qualities and just love yourself for those(:
Almost every person has stretch marks or has at least HAD them at some point or another, I highly doubt the person will give it a second thought, if they don't and say something hurtful about them, then theyre acting a bit childish. I strongly encourage you to check out these products here: link