Thanks for your query.Based on the facts that you have posted it appears that you have prominent vein on your foreskin running from glans
to tip of the foreskin.
This is normal superficial vein
on foreskin and there is no chance of it getting it injured unless you are too vigorous in your sexual activities.
If you have problem in retracting your foreskin consult qualified General Surgeon
for clinical assessment .You may need to get circumcised.