Advice Needed

A and B are lovers.
A and B are together frequently.
A soon discovers that B has traits he can't tolerate.
B starts to complain that A is bossy and takes B for granted.
A and B begin to have petty fights often.
A has some time off, and realizes he misses his "me" time.
More importantly, A realizes he wants out.
A cannot see the relationship with B work out anymore.
A is awkward with initiating break-ups, and does not know how to go about it.

Please help A.
How should he do it?