One can be called to marriage, or called to remain single. One can be dedicated to God in either case. It is much harder if one misses one's calling and tries to take the opposite path, which God did not form that person for. (However, He can still give grace and redeem our mistakes but we must cooperate even more closely with Him in order to do well in that case.)
Other than that, the question seems to make certain assumptions about a life dedicated to God.
One can become a monastic, unmarried, devoting all time and energy to God in the context of a community (or rarely, alone). That is often called "the angelic life" because like the angels, they are freed from cares regarding carnal relations and also don't have to consider a spouse within their decisions.
But married persons are just as legitimately able to live lives devoted to God. Service to and love for the spouse, putting their greater good over one's own desires, is a form of sacrifice and agape-love, making us like Christ. Raising up children in the Lord (whether natural or spiritual) is one of the highest callings. Everything we do in life or work can be done unto the Lord. Ideally we would strive to do this, whether married or single.
In some ways it's easier for singles. But they have particular challenges too. Just different ones.