Depends on his reasons for it. Is it a better paid job? Something he's always wanted to do? Can it help his career?
My DH works over 900 km (600 ish miles) away from home during the week. He'd been out of work for 3 months after his last job made him redundant. This job is the first that came up that he's been offered. We have a mortgage to pay and a 12 year old DS to support so we can't be fussy.
My DH worked like that for a year about five years ago. Flying out on a Monday morning and returning on a Friday evening. I coped fine when DS was 7 years old and so I don't have many problems now he's more independent. We got into our routine. I work part time, things get done when they can get done and DS helps as much as he can with washing up etc without skipping homework or missing out on normal '12 year old' stuff.
But, I know DH would rather be here. Although he's taken the job he's still looking for something closer to home - his field of work is quite specialised so you have to take the work when/where it comes up.
We have friends where the DH was away for 6 weeks at a time including weekends, in a middle eastern country. My friend had 2 kids under five at the time. But it was where he could earn enough to set them up by paying off the mortgage so they discussed it and did this for four years - 6 weeks out, 6 weeks back. My friend is an ex-pat child so she was used to living abroad or dad being away for periods in her life so she settled into her routine very quickly.
Many, many families only see each other at the weekends or when one half is 'off duty' like the armed forces or specialist workers where the work takes them abroad.
It does depend on the relationship you already have and your own attitude towards it. DS and I work as a team when DH is away, some chores wait and DS and I try to have 'snuggle times' once his homework is done (put on a DVD and have a TV dinner) once a week as a treat for getting on with it!
Our weekends usually mean a quick catch up on chores that need to be done on Saturday mornings, then a family treat (cinema or a nice meal out or a trip to the seaside etc). DH also does all the ironing for the family on the Sunday evening before he goes as he knows I'll be in charge of everything else. It's a chore that he can do for the week, most others have to be done on a daily basis.
And he 'gives' me 'me' time by taking DS out on his own at some point over the weekend - I can either slob in front of a film or get out and about - my time. It was his way of contributing and I'm grateful for it. He gets his down time in the hotel he stays in when he's working - not much else he can do!
It can make the relationship stronger because you appreciate them when they are home but it can ruin it if there's resentment. I know DH is stuck in a hotel room most of the week, he knows I'm keeping the home together at this end so we appreciate the sacrifices we're both making. I think a lot has to do with DH's attitude when he gets home at the weekend. He sees it as his job, as DH and DF, to make sure his family are set for the coming week - hence getting heavy chores done, getting all the ironing done and giving me a break.