To find your first boyfriend, you need to go to the clubs first.

It will take you to a place like this:

There are 5 clubs. 4 of them are already unlocked, and one of them unlocks at level 30.

You can only date 1 boyfriend at a time.

Find the boyfriend that you like.

Click on him, and it should take you to a page like this:

It shows you the name, the job, the skill bonus, the gifts collected, and a description. It also shows you what he looks like.

If you decide that that is the boyfriend you want, click the flirt button, and you will now have a boyfriend!