Warning - I know I risk sounding mega weird but I really can't ask my friends of family this; so you will have to do! 
I particularly love the name Sebastian but had a long term ex-boyfriend with a similar name (the Dutch derivative Bastiaan which has the nick name of Bas as opposed to Seb).
Do you think that the names are different enough to not be associated?
Would you be able to name your son and not associate it with an ex if you really liked the name?
Its my OHs favourite name (he's not bothered about the ex-factor) and I love it too but worried that I may have a change of heart one day and concerned of what others may think!
Over to you!
Many thanks