How to overcome fear for lost of opportunity? I get fear when I'm trying to choose something over buddhist teaching.

Listening to Dhamma instead of studying something else
Reject a job offer to get some free time
Not having relationship (with a person who have great qualities) because it increases clinging, lust etc. and it causes suffering

My doubt is that those opportunities may help my journey to enlightenment.

Having a good job may make free time later
Good person may help me to understand buddhism more.

So, How can I decide what to give up and what not to give up ? Prince Siddhartha gave up lot of great things. (Kindom, Wife, Parents). But I don't have such a great mind like him. I have ignorence. So how to overcome this fear? Did Lord Buddha mention these kind of situations in his teachings?
In Buddhism, you can choose to be a lay follower, who observes the five precepts and the non-noble version of the path (which has defilements remaining) as a lay person, or you can follow the Noble Eightfold Path of a monk who renounces the worldly life.
If you choose to be a lay follower, then you obviously need a source of income and you can choose to have a life partner - in both cases, subject to the five precepts, Right Action, Right Speech and Right Livelihood. You may also need to spend some time learning non-Dhamma knowledge that may help your worldly life. To feel guilty or remorse for any of that is not skillful.
Please read this answer to &quot;Can a Buddhist own and run a billion dollar business?&quot;. That should remove your doubts about the lay follower path. Also in this answer, you can see that lay followers are told to set aside some time for meditation. Also please read this answer to &quot;Is it “bad” to want a “materialistic” happiness?&quot;
So, you should make your choice of being a lay follower or a renunciate, and follow the path laid out, without feeling guilty or remorse. You can also change your mind later. But don't choose to remain a lay follower and feel conflicted about it - that's unskillful.