OBJ files exported from Wings3D do not load in Sweet Home 3D

[micheus]

No one has reported that before. I have other applications that are able to import your file without any problem. I think they manage that better.

The "//" came from this reference (OBJ file specification):

Using v, vt, and vn to represent geometric vertices, texture vertices,
and vertex normals, the statement would read:

f v/vt/vn v/vt/vn v/vt/vn v/vt/vn

If there are only vertices and vertex normals for a face element (no
texture vertices), you would enter two slashes (//). For example, to
specify only the vertex and vertex normal reference numbers, you would
enter:

f 1//1 2//2 3//3 4//4

or from this other

In the export dialog you can set Export normals/smoothing group and your file will contain something like this:

...
g coupelle4b_Coupelles
usemtl Coupelles
s 1
f 129//129 161//161 162//162 130//130
f 129//129 321//321 352//352 160//160
...

and you probably will not have problem importing it again.
Or, you can try to use the DAE and 3DS exporters, since they are accepted by Sweet Home 3D too.