Among the usual quota of general boyfriends, I have had a sixth form boyfriend who was also my very Best friend (2 years) a first fiancé late teens/early twenties (2.5years), and my husband whom I met when I was 24.
When my best friend-boyfriend and I split up I felt lost and bruised, and was young and foolish enough to meet several boyfriends while on the rebound - including the first fiancé a year later. I regard that relationship ending, as the best bad thing that ever happened to me - as I realised within 6 months of breaking up that it would have never, ever worked out happily for us. We were too unsuited.
I learned from my first broken relationship that for me, getting serious with someone else, while feeling vulnerable was a disaster for me, I couldn’t be objective enough.
I dated casually for several years, after splitting up with my first fiancé, very mindful of not getting serious again, until meeting my husband (currently m 41 years).
It is of course different for everyone. You have to be very honest with yourself.
It certainly helped me cope, even though I was lonely at intervals, I realised plunging straight back in was not the answer for me, until I was in a genuinely better place.