How to deal with insecurities and neediness in relationship?

I’m the one creating 90% fights in my relationship because of neediness and insecurities.

I’m too much needy. Also feel insecure when she go out alone or with male friends (because most men would look for a chance to flirt)

How to deal with this guys?

Need matured, practical advice from 25+ aged people.

Below 25 and single sentence answers can skip
How to deal with insecurities and neediness in relationship?
Post Opinion