When the kids come to visit, the man often does not know quite what to do with them. Older kids have to miss being with their friends to see their father, and this resentment is layered in with whatever feelings the children may be having toward their father. Loneliness leads to bitterness. Typical reactions are to suppress the emotions, and channel the loneliness into bitterness and anger. You should try not to let this happen.
Loneliness leads to remarriage.
Another typical reaction is to find another woman quickly. Many men remarry within one year of the divorce. Statistically speaking, this is usually too soon for them, and for their children. Take your time. Therapists suggest that you admit the loneliness, and take time to adjust.